The Crimson Chin from The Fairly OddParents wears a suit and glasses. Never mind that his super hero suit is worn underneath it including his face mask. In fact a his suit seems permanently attached to him as he's never seen without in even wearing civilian clothes.
Played for laughs in Ed, Edd n Eddy. Eddy goes temporarily insane from pure boredom and Double D decides he and Ed will have to capture Eddy for his own safety. So they approach Eddy wearing poorly drawn paper masks of Johnny and Plank. Eddy in his current state totally falls for it.
Bonus Points: Ed's mask actually falls off at one point! Leading Double D to Face Palm, Eddy reacts with the following:
Eddy: Johnny...you dropped your face. (Beat) I'll get you a new one! (runs off)
The "Chicken Boo" segments of Animaniacs are based almost entirely on essentially parodying this trope. Boo himself is simply a giant chicken that cannot speak and is not anthropomorphic in any way (besides apparently having opposable thumbs), yet when he puts on a wig, a mask, a mustache, or a suit, everyone is fooled into thinking he is one of them. Not just one of them however, but an expert in whatever field he is pretending to be involved in and often with a fully established backstory of some kind. The Cassandra will try to convince everyone that he is just a chicken but will be laughed off by everyone else until Boo's disguise comes off, at which point he is immediately recognised as not being human, The Cassandra will return to rub it in their faces, and Boo is chased away by an angry mob.
Theme Song: You wear a disguise to look like human guys, but you're not a man, you're a chicken, Boo.
In other Animaniacs cartoons, however, this trope is often played straight. Characters are often completely fooled by when one of the Warners puts on a disguise and an accent.
Subverted pretty regularly in Slappy Squirrel's segments. Her opponents often resort to this (Among other stock cartoon tactics) to try to get the better of her, but she's so Genre Savvy she sees through them right away.
In one, Daniel Boone tries to dress as a bird to get at Slappy's tree, but the disguise is "pretty absurd" (as the chorus acting as the Interactive Narrator clearly says) and Slappy doesn't fall for it.
In Avatar: The Last Airbender , the kids' disguises include Aang wearing a wig and moustache made of Appa-fur and pretending to be an old man, and Sokka and Katara donning a moustache and fake baby-bump respectively and pretending to be Aang's parents. Completely believed every time.
It seems that all Aang ever has to do is cover up his arrow, and he's safe. Eh? That kid with a turban has the same yellow and orange garb as the Avatar? Well phooey, we can't see his arrow! There's no way it's him!
Though, admittedly it got a lot better in the beginning of Season Three, what with completely different clothes, actual hair, a headband, and an attempt to assimilate.
Also, it seems like people generally don't know his appearance that well... after all, there's no photography in this world - all they have is colorless drawings, and that's only in the Fire Nation.
It makes sense with Katara and Sokka most of the time because (for whatever reason) the Fire Nation never made wanted posters for them.
In the episode "Sokka's Master", at the very end Piandao reveals that he always knew Sokka was a member of the Water Tribe, since the name "Sokka" is very distinctly Water Tribe in the series. He recommends, for future reference, the name Li. "There's a million Lis."
Also Zuko and Iroh while on the run from the Fire Nation in season 2. Despite being on hundreds of wanted posters throughout the Earth Kingdom, no one ever manages to recognize the angry teenage boy with a huge scar traveling with his short, chubby uncle as the two fugitives on the poster.
Or, from a Fridge Horror perspective, an angry teenage boy with a giant burn scar on his face living homeless with an elderly uncle could actually be pretty common.
In season 3, "The Painted Lady" this trope is both subverted and averted. Katara dresses as a Spirit to help a town who's river was polluted by the Fire Nation's factories. It's actually quite a brilliant disguise, and with the help of her waterbending, she's very convincing (at least until Aang catches her sneaking off). On the more comedic side, we have a man who seems to be completely insane. He switches hats and names, telling the gang he's a trio of brothers.
"Xu": I'll get my other brother, Bushi! He loves cleaning rivers! (removes his cap, a straw hat flops out from under it) Okay! I'm Bushi!
Aang: I knew it! You are the same guy! You just switched hats and called yourself a different name!
"Bushi": Oh you know who does that? My brother, Dock. He's crazy.
In an episode of The Backyardigans, Pablo self-proclaimed himself as "Le Master of Disguise" (which just happened to be the episode's title), and he couldn't be recognized by any of the other characters, most especially when he dressed up in the costume Austin was wearing at the episode, mustache and all (though Pablo's was over his beak), and the others couldn't tell them from each other, even if Austin and Pablo looked nothing alike.
An episode of Camp Lazlo had Lazlo, Clam, and Raj sneak into the Squirrel Scouts camp with Lazlo and Clam dressed as girls and Raj disguised as a log. None of the Squirrel Scouts seemed to notice.
In another episode the Beans Scouts fool the Squirrel Scouts by saying they have a unicorn which is actually a filthy disgusting llama with an ice cream cone on his head, later when they take the cone off they proclaim "He's hideous!" despite finding him beautiful earlier.
Amusingly subverted in Chowder; in an escalating effort to convince Panini that He's Not Her Boyfriend, Chowder turns up on her doorstep wearing a large black moustache and fabricates a story about the "real" Chowder moving far away. Panini still knows it's Chowder, though. In the end, he foils himself after he gleefully accepts the cookie she offers him.
On one episode of Clone High, the clone of Joan of Arc had to dress as a man by wearing a fairly obvious fake moustache that nonetheless fooled all of the other characters, because the basketball team wasn't allowed to include girls or animals. When her disguise is penetrated, her place is taken by a dolphin in an equally fake moustache.
Subverted in the episode where Homer gets banned from Moe's Tavern. Somebody who is "obviously" Homer in a bowler hat with a monocle and fake mustache walks into Moe's, speaking in an oddly stilted manner with a British accent. He protests that he's not Homer, but the innocuously named Guy Incognito, but gets beaten up and thrown out anyway. Outside, we see Homer walk past the barely conscious heap of the undisguised patron, then briefly reflect upon the implications of finding a perfect copy of himself. And then on a dog with a puffy tail.
In the episode "Marge vs. the Monorail", Mr. Burns tries to pass himself off as "Mr. Snrub", wearing nothing unusual besides a long moustache. It does not work.
Possibly the most absurd example of all: in a parody of The Count of Monte Cristo, the Count (Homer) removes his mask, and nobody recognizes him. Then he removes his fake mole, and everyone in the room gasps in shock.
Another example of it not working is where Mr Burns dresses up in Jimbo's clothes to inform Principal Skinner his fourth-form chums and he think it would be quite corking if he were to give the school's new riches to the local energy concern. Naturally Skinner isn't fooled: "It was naive of you to assume I'd mistake this town's most prominent 104 year old man for one of my elementary school students"
In "Kamp Krusty", the villainous Mr. Black attempted to keep the campers already lowered morale steady by hiring someone to pose as Krusty. The person he hired was Barney Gumble... whose disguise involved nothing more than slapping him in Krusty's clothes (that barely even fit him, anyways), wearing a skull cap representing Krusty's head and some makeup. Most of the kids were suspicious, and Bart ends up pointing out that he's an impostor. Barney himself unwittingly confirms it simply by speaking (his drunk voice was heard instead of Krusty's voice, not to mention he called himself "Krunchy the Clown.")
Mr Burns, Smithers, and an Assassin they hired dress up as Marge, Bart, and Homer respectively in order to infiltrate the nursing home and kill Grampa. Grampa sees through the deception... because his family never visits him.
In "Hungry Hungry Homer", Duffman disguises himself in this manner as a news reporter named Joel Duffman, from The Newsly Times.
Played straight in an early episode when Bart takes up ballet, and disguises himself by wearing a balaclava - in spite of his distinctive hairstyle remaining clearly visible. Everyone is fooled, and nothing much is made of how ridiculous it is.
Subverted in one episode where Bart ditched class. When he saw Homer, he quickly pushed his hair forward hoping to fool him. However, Homer has already seen Bart and was afraid the boy would figure out he ditched work. Homer's disguise was putting a hair comb under his nose as a moustache. Homer and Bart just pretended they didn't recognize each other.
In the episode "Burns' Heir," Burns shows Bart a "live broadcast" of Bart's family talking about how much they don't want him to come home. In reality, it is a group of actors Burns hired, including the Estonian Dwarf as Lisa. Bart is unconvinced until Fake Homer says his famous catchphrase "B'oh."
Also used in the episode where Homer becomes the Batman-esque Pie Man. At the end, Marge finally reveals that she always knew, just because it was so obviously him.
In "Lisa Goes Gaga," Lady Gaga disguised herself by putting on sunglasses and a grey hoodie. However, the hoodie had "GAGA" written on the back in blinking letters and it was rigged with sound effects to make it say, "Gaga Gaga Gaga."
In "At Long Last Leave" Homer and Marge try to sneak into town as Mr. Burns and Smithers. While it seems to fool Chief Wiggum, it's only because he went to get the others. He points out while dumb, he's not that dumb.
An episode of Hey Arnold! entitled "Helga's Locket" featured this when Helga attempted to get her locket of Arnold back from Arnold's grandpa. She disguised herself in a black trenchcoat, a derby, glasses, and fake mustache, passing herself off as "Bernard Flotsom", a rich antique art collector. It works for maybe a minute, and after a couple of near-misses (such as one of her pigtails poking out from her hat), Grandpa gets wise once she runs off with the locket saying, "So long sucker!" As she runs off, Grandpa, now mistaking her for some hooligan, calls out "AND YOU FORGOT YOUR MUSTACHE!"
In the episode "Suspended," Harold is suspended from school. When he discovers that being suspended isn't all it's cracked up to be, he repeatedly attempts to sneak back into P.S. 118. At one point, he hits upon the idea of pretending to be a pizza delivery man, and so dons what he dubs a "foolproof disguise": a fake black mustache, chef's hat, apron, and a striped shirt with his name on it. Unsurprisingly, Principal Wartz isn't fooled by the trick, even when Harold attempts a horrible Italian accent to convince him.
Subverted in an episode of Family Guy: Peter is at the supermarket and partakes in a free sample, saying that it was quite good. Afterwards, a man identical to Peter wearing a Groucho Marx disguise takes a sample, then another Peter with a thin mustache and oriental haircut (plus a horrible Japanese accent). The employee informs him that he doesn't have to disguise himself to get free samples. Suddenly, Groucho Marx Peter and the actual Peter walk up behind him and ask if they can have another free sample.
Also in Family Guy, all it takes to be completely indistinguishable from the real Lois is to wear a green button-down shirt, beige pants, and orange wig. It is not necessary to fake the voice, the body shape, the ability to walk... Even just wearing her shoes, earrings, and lipstick is enough to confuse people, if not convince them.
In one episode, Brian tries to avoid Stewie over some unpaid debts. To try to sneak past him, Brian dons an elaborate mustache, and just that. He does manage to make it past Stewie with only a "good day sir" at first, but Stewie catches on after the double take.
There was the one where Peter went to his high school reunion pretending to be a space cowboy but one guy didn't believe him because his hat comes right off. A similar gag was done in "Road to Germany" when a Nazi found out Mort wasn't a priest by removing his collar.
In addition, Old Man Herbert attempts to disguise himself as a fifth grader for the school dance, for obvious reasons. However, Brian apparently sees through the disguise, and humiliates him by talking about stretching his "creamy hamstrings."
Used in The Powerpuff Girls, when three adult-sized (male) crooks put on Powerpuff Girl costumes and somehow manage to deceive the entire town.
Not to mention, once they meet up, the girls themselves and each other. And the disguises were merely correctly-colored clothing and cardboard cutout masks.
The only one not fooled by the disguises was Ms. Bellum; she saw their body hair and bad manly body odor, and the fact that they kept hitting on her.
Also used when Mojo Jojo goes to the Powerpuff Girls' slumber party disguised as a little girl. Though the Powerpuff Girls (even Bubbles) aren't fooled, the other girls and the Professor are.
Or when Mojo Jojo sneaks into a show and tell of the Professor's time machine, by disguising himself as a preschool student. Which this time seems to fool everyone, including the girls and their teacher (who is one of the more responsible and competent characters).
In South Park, Towelie assumes a fake moustache and a hat in order to get his "A Million Little Fibers" book published. The first person to realize this is Oprah Winfrey's sapient vagina.
Played with when Cartman disguises himself as AWESOM-O the robot. Butters's relatives have no trouble figuring out that he's just a kid in a cardboard costume, but everyone else is convinced that he's a genuine robot, up to and including the military.
Another episode had a male cop who went undercover as a female prostitute for sting operations. He didn't even shave off his mustache or change his voice at all and still fooled everyone.
Played for Laughs in the third Halloween episode, where one of the costumes is an incredibly well-made (and apparently fully functional) Mecha. But everyone who sees it instantly knows it's Kenny, much to his frustration.
Played for very dark laughs in "Good Times With Weapons". When the boys accidentally throw a ninja star into Butter's eye, they put him in a crummy dog disguise meant to fool an old, half-blind veterinarian. However, when Butters wanders to a hospital, the doctor and nurse who find him are convinced that he's a real dog and send him to an animal shelter. The workers there are fooled too, to the point that they try to put him down.
After failing to get the Triangle of Zinthar from the boys, Barbra Streisand dons a fake mustache and glasses on her second attempt. The boys are fooled and freely mock Streisand in her presence, much to her indignation.
It gets lampshaded in the Banana Formula story when Boris worries how, after all the times Rocky and Bullwinkle have never seen through his disguises, the Law of Averages was sure to turn on him. Natasha reassures him by pointing out that Good Is Dumb.
In DuckTales, no one ever recognizes the disguised Beagle Boys under the fake mustache (or whatever), even though they always wear their robbery masks and prisoner numbers. Considering even their own family hasn't seen them without the masks, simply removing them might be far more effective than anything else they could do.
In a (non-DuckTales related) comic story, this is lampshaded by the Beagle Boys ridiculing one of them when he pulls off a disguise that's actually somewhat more convincing than most others, since he actually bothers to make the mask less noticeable by wearing huge glasses. Earlier and later in the story, the other Beagle Boys had worn disguises that didn't even cover any of their faces.
Thoroughly subverted in an episode of Samurai Jack, "Jack And Swamp Monster". The hermit that guides Jack through various perils is very obviously Aku, Jack's arch-enemy. Jack is apparently oblivious to the fact that his new-found ally has the same color eyebrows (red), the same color skin (jet black), as well as the same voice and attitude as Aku. At one point, even the hermit's reflection in water reveals his true nature, leaving the viewer questioning Jack's sanity as he sinks deeper into Aku's trap. At the end of the episode, however, Jack reveals that he knew the truth all along, and that he's merely been playing along in order to trap Aku. The entire episode also serves to hang a lampshade on Jack's general genre-blindness; he's been tricked by Aku before in similarly transparent disguises (and, admittedly, one really good one).
Although getting tricked by a full on shapeshifter who can change anything about his appearance isn't something to be terribly ashamed of.
Invader Zim utilises the "brilliant" disguise of a wig and contact lenses, leaving his three-digit hands, green skin and lack of ears and nose exposed, a fact that only Dib recognises, while his robot henchman's disguise is a bright green dog suit with obvious zipper and stichings. Glimpses of other Invaders shows their disguises as equally pathetic, so it isn't just him. The trope is averted with Tak, who is shown to be a supremely competent Invader the moment it is revealed that her disguise is actually effective.
The paper-thin disguise is in effect to the degree that at one point one of Zim's contacts falls out, which a small boy sees and begins screaming "ALIEN!". Zim promptly puts the contact back in and the boy says "Oh, never mind."
In another episode, he dismisses it as Pink Eye.
And of course when Zim gets abducted by Sizz-lor, his former boss/warden, he fails to recognize him. While at first this is somewhat justified because Sizz-lor is wearing a gas mask and body suit, when he changes back into his normal fry cook outfit, Zim still doesn't recognize him until he puts his hat on, despite his face and NAME TAG having been revealed first.
In "The Girl Who Cried Gnome" Zim's disguise is just a bear costume and when there's a news story on him later the artist's depiction has a normal human face.
Then there were the 2 mantis-like aliens from "Abducted" whose costumes consisted of aprons with human bodies printed on them and paper mache masks on elastic strings. Even Zim isn't fooled.
An episode of the 2006 revival of Biker Mice from Mars called "It's The Pits" has Dr Karbunkle wear a fake beard in some scenes.
Hip-Hip and Hurra from Hip-Hip and Hurra use them all the time. There are a few rare examples when the disguises actually work.
In Kim Possible, Shego donned a wig and a dress to pull off a Show Some Leg distraction on a guy she'd previously tried to hold for ransom. She succeeded despite doing nothing about her green skin. Even after the wig fell off, the guy still wanted to date her.
Averted with Camille Leon, except in her second appearance.
In The Maxx, the Big Bad's sidekicks Isz, which looked like small black chess pawns, could be disguised as anything with minimal effort. Put a gray wig and purse on them, they appear as a little old lady. Hand them a bottle of cheap wine in a paper bag and they're a hobo.
In The Replacements, when the rest of the Daring family decides to tag along on Riely's first date, they do so by donning false moustaches and posing as wait staff. This includes the talking car. This doesn't fool Riely but apparently fools her boyfriend (and leads to the brilliant panicked line of "That could be anybody's talking car!").
Evil The Cat tried this twice in Earthworm Jim. Oddly enough, it failed miserably in one episode (Evil took four Super Blaster shots to the face, once for each failed costume) and worked perfectly in a later episode.
And in the times that his disguise did work, he'd introduce himself by saying, "I am (whatever I'm disguised is) and not a cat. I'm here to (do whatever it is I want you to think I'm doing). And did I mention I'm not a cat?"
Psycrow and Professor Monkey-For-A-Head also managed to steal Jim's suit by disguising Psycrow's ship as a Laundromat (as in, just hanging up a sign saying it's a landromat and NOT Psycrow's ship.) Inside was the Professor dressed as a cowboy with a fake mustache and gigantic hat to hide the monkey. When a banana peel falls out of his hat, he just blames it on head lice.
Jim himself also manages to hide from a killer robot inside his suit by attaching himself to a wall and proclaiming "Hiss hiss! Hello! I am a steam pipe. The intruders went that way! Hiss hiss! Steam!"
Happens again in "Toddler Terrors of Time Travel", where Bowser and Kooky pretend to be plumbers in Brooklyn and intentionally clog someone's drainpipes.
Happens once more in "Send In The Clowns", where Mario and the cave people don't realize the clowns in Bowser's circus are actually Rexes until one of their noses falls off.
Subverted in "Reptiles in the Rose Garden" when the brothers try to sneak onto Bowser's ship wearing Hammer Suits. The first Sledge Brother they approach takes one look at them, and without missing a beat asks, "Putting on a little weight, aren't you, Mario?"
Double subverted in "The Beauty of Kootie". Kootie Pie's realistic human disguise fools Mario, despite her Cheatsy forgetting to remove her tail.
A subversion similar to the "Guy Incognito" example above occurs in the SpongeBob SquarePants episode "No Weenies Allowed": trying to get into a tough bar, SpongeBob hits upon the idea of wearing a tough hairdo. Cut to what appears to be SpongeBob with a black pompadour out of The Fifties approaching the bar. The bouncer is unimpressed and tries to unmask him... until the real SpongeBob appears wearing a rainbow wig.
Done again in "The Slumber Party". SpongeBob and Krabs must sneak into Pearl's slumber party to make sure she's not destroying the house. The scene then cuts to a girl who's obviously SpongeBob knocking on the door and trying to get into the party. Her name is "Girly Teengirl" and she just moved in from "Farawayville". Pearl quickly decides that she is Spongebob, Pearl's friends throw tomatoes at her, and she runs away, shouting, "I'm so moving back to Farawayville!" Then Krabs and SpongeBob pull up in a pizza truck, and SpongeBob sees the girl and comments on her looks. SpongeBob proceeds to play this trope straight by wearing a fake mustache; this disguise holds for a few seconds until the mustache flies away.
Played humorously straight in "Imitation Krabs." Plankton builds a robot doppelganger of Mr. Krabs that's obviously a robot, complete with monotone robot voice and exhaust pipe. It fools everyone, especially SpongeBob.
Actually, Squidward wasn't fooled by Plankton's disguise. He just decided to play along because "Imitation Krabs" told him he could take the rest of the day off.
Also played for laughs in "SpongeBob Meets the Strangler". The strangler uses only a fake mustache as disguise (a detailed scene has even the price tag attached to it) and it actually fools SpongeBob.
Again played ridiculously straight in "Shellback Shenanigans", where Plankton disguised himself as Gary and not only fooled Spongebob, but also fooled the Bikini Bottom doctors!
Batman looks and sounds the same as Bruce Wayne, but aside from Wonder Woman and Ra's al Ghul, very few people in the DCAU seem to notice the resemblance.
In most of his incarnations, Batman's voice and body language are very different from Bruce Wayne's, and Wayne makes himself too big of a fop to be taken seriously. But one wonders why it isn't obvious to everyone besides Ra's Al Ghul that he funds Batman's operations, since he's the richest man in the city, and the only one with unlimited access to the kind of technology Batman routinely uses.
Wayne's not the only game in town when it comes to rich people with advanced toys. By that standard alone, Lex Luthor and Vandal Savage are also likely candidates.
He further covers his back when explaining to his mechanic he has "backers" with dummy companies funding his crusade. Which does bring back the question if Bruce Wayne is one of those backers.
Commissioner Gordon somehow fails to recognize his own daughter, despite the fact that the mask doesn't even cover her eyes, nor does she use a different voice.
One version implies he does know and is a Secret Secret Keeper because things would be difficult otherwise.
However, in "Never Fear," Wayne reprises his Matches Malone alias, but looks exactly like Wayne in his standard TNBA business suit, and wearing a pencil thin moustache and possibly sunglasses. None of that wardrobe and make-up artists' effects seen in "Shadow of the Bat."
In the third episode of Transformers Generation 1, the Autobots decide to set up an ambush for the Decepticons. Hound uses his holographic projector to make a fake "rocket base" and the Autobots will be in it, under disguise, to attack the Decepticons when they show up to raid the base. What disguise do the Autobots go for? If you guessed "Disguised in their car mode in the base parking lot", congratulations, you're smarter than an Autobot. They decide to don labcoats and pass for the human scientists. Despite the fact that even the smallest of them is twice as tall as a human and about 3 times as wide.
Almost used in Transformers Cybertron. After Bud describes conventions and cosplay to the Autobots, Jetfire jokingly suggests that they pretend they're fanboys in public, to the amusement of all. However, Optimus Prime takes him seriously and thinks this is a wonderful idea until the humans talk him out of it.
And then there was Transformers Armada, when the kids dressed up the Space Team in lumpy sweaters, scarves, and goggles to take them on the bus. And it worked.
Punch/Counterpunch, full stop. His Autobot counterpart is reeeal nearby... Only exacerbated by the fact that his "second robot mode" basically consisted of turning around, lowering his shoulders, and pulling up a visor.
Bugs Bunny can pretend to be a human by simply wearing human clothes. This cover is usually blown when someone notices his tail or ears. Of course, no one bothers to notice the gray fur or obviously non-human face...
In "Forward March Hare" (1953), the sergeant-demoted-to-private only notices the ears pretty far along, and then mentions the fur before realizing the Army's inducted a rabbit by mistake.
In "Bowery Bugs" he impersonates several different people from a swami to a police officer, all by just changing clothes. When the villain of the short finally catches on, he mistakenly thinks that everyone is turning into rabbits, goes insane, and hurls himself off the Brooklyn Bridge.
During the "hunting trilogy" he impersonates everything from a woman to the Game Warden, Elmer is fooled every time.
An episode of Tiny Toon Adventures did the same thing in an episode where Babs Bunny pretended to be a human simply by dressing like one so she could star on a teen drama. It was even lampshaded when the makeup guy told her she should consider getting a facial wax to remove excess hair. Why the various other times the species of the characters didn't matter to other humans (including the ones that went to school with them, aside from Elmyra) is ignored.
In the Looney Tunes short "Dough for the Dodo", Porky Pig fools the Dodo by wearing only a ragged green coat and an umbrella on his head. However, in the original short "Porky in Wackyland" (which was the former was a remake of), Porky had a very effective disguise wearing a false beard that covered everything but his eyes, a false nose and glasses, a different coat, and a helmet with a light bulb on it.
Another Looney Tunes example, though this counts as a subversion: In "Dog Pounded", Sylvester puts on a dog suit to infiltrate a dog pound where Tweety is hiding. So unconvincing is this disguise, that the dogs inside see through it immediately and attack, forcing Sylvester to make a quick escape. Later, a Double Subversion occurs when a dogcatcher notices the still-disguised Sylvester and inattentively throws him back into the pound, where another mauling awaits.
Bugs explained this phenomenon himself to Buster and Babs in the first episode of Tiny Toon Adventures: "Eh, you'll be fine if you remember t'ree things. One, your adversaries have tapioca for brains. Two, always eat your carrots. And three, villains always fall for cheesy disguises." The last line was said while briefly disguised in a shabby-looking Taz costume (which still manages to scare Buster and Babs). The next scene (at Montana Max's) has Babs recall what Bugs said about cheesy disguises, and the two dress up as Yosemite Sam (Buster) and Elmer Fudd (Babs) to fool Montana Max.
Bugs Bunny is so notorious for flimsy disguises that somehow work that, if this trope was up for a re-naming, "Bugs Bunny Disguise" would be an excellent choice.
Subverted in one cartoon when a watchdog is trying to protect chickens from a nearby fox. The fox trims the hair on his face and tail to masquerade as another dog wanting a job. The watchdog sees through it right away, but he decides to play dumb and puts the fox through hell.
In Merlin the Magic Mouse, upon learning that the sole person in the audience is a cat, Merlin hides the fact he's a mouse by wearing a mustach. The cat is fooled until it falls off.
Subverted in Hollywood Daffy, when Daffy tries several disguises to get past the guard, but none of them work.
Played with in Tortoise Wins by a Hare. In an attempt to learn how Cecil Turtle has been able to beat Bugs at every race, Bugs dons a disguise consisting of a long grey beard, sunglasses, and a hat (which he hides his ears inside of), and Cecil gives him information. But it turns out Cecil knew all along that it was Bugs, and was merely tricking him.
Also subverted in Backwoods Bunny, when Bugs is pitted against a dimwitted hillbilly buzzard. At one point, Bugs pulls his old dress-in-drag routine, and initially, it appears to work until the buzzard reveals that he wasn't fooled in the slightest.
Subverted at the end of Don't Give Up the Sheep, when Sam clocks out, [spoiler he instantly notices that the sheepdog who clocks in to replace him is Ralph in a very convincing sheepdog disguise and beats him. Though it could be he regognized the voice when he greeted Sam.]
In "Nuclear Confusion", Dexter poses as a stuffed swordfish by clenching a poker in his mouth. Of course, his dad doesn't notice anything.
Another one had Dee Dee accidentally shutting down the lab and spending the entire episode tricking Dexter into thinking nothing is wrong by impersonating Computer, Robot, and Mandark. Somehow this worked and Dexter is none the wiser. "Boy genius" my ass.
In another episode, Dexter grows a beard and no one seems to recognize him. This is taken to hilariously ridiculous levels when he encounters his TV hero "Action Hank", who is huge and black, unlike Dexter, who's short and redhead, yet people actually mistake one for the other.
Thug 1: Two Action Hanks!. Thug 2: But which one is the real one?.
"Momdark". Mandark kidnaps Dexter's mother and dresses up as her. His disguise is actually quite good, except for the huge glasses on his face (which she doesn't wear) and his voice, which doesn't sound like hers at all. However, it fools Dexter, Dee Dee, and their father completely.
Mr. Boss ridicules the Toilenator by mentioning that he was once fooled by Numbuh One in disguise, even though the disguise consisted solely of a T-shirt that said "I am not Numbuh One." (Of course, the Toilenator isn't all-too bright...)
In Operation: C.H.A.D., Mega Mom and Destructo Dad's full-head helmets pretty much resemble exaggerated versions of their actual faces, and don't hide their voices at all; yet, for some reason, this is enough to conceal their identities from their own son until they remove them.
And in the KND crossover with The Grim Adventures of Billy & Mandy, The Grim Adventures of the KND, Numbuh One's tomato-nose Billy disguise is intended to fool Billy's dad... but fools Grim before Dad can even get home. And when Mandy disguises herself as Numbuh One with his sunglasses and shirt, she fools the entire KND organization and takes over!
And changes the name to "Mandy", no less.
Numbuh 4-30teen-7 manages to get into a girl's slumber party. Though since the show itself would lampshade and subvert tropes, it's debatable that the girls may have known all along and merely acted surprised when his obvious wig fell off (they're supposed to be Genki Girls in general, closet or otherwise, but maybe that would be the point of their apparently not seeing through the disguise, rather than having IQ levels stereotypical for that).
It's unlikely that the girls knew all along-they seemed genuinely surprised when Numbuh Four's wig fell off. Plus, Numbuh 86 clearly didn't want to invite any boys.
Pretty much any disguise Pinky and the Brain used. Keep in mind...they're lab mice. And just a few inches tall. And yet, could be mistaken for humans, with the right outfit. Brain even points this out numerous times to people, though they pass it off as Sarcastic Confession:
Taxi Driver: Hey man, not to pry but... what happened to your head? Brain: Nothing. I'm a mouse in a large mechanical suit. Taxi Driver: Oh. My fault for asking.
Sometimes he doesn't need a disguise. Once Brain got pulled over by a cop while riding a modified motorcycle. The cop just thought he was a child out for a joyride.
Cosmo and Wanda from The Fairly OddParents have passed, floating and all, with signs that read "Normal" and "Human", respectively. They don't even bother with a disguise at a comic convention, as everyone assumes they're wearing costumes.
This happened again when Cosmo was being taken to the doctor. His main disguise is a green lamp with the words "Not Cosmo" written on him. This was only made worse by his line "A LAMP!!! The perfect disguise!"
Timmy's had a few, but the disguise in "Shiny Teeth" takes the cake: by simply wearing a tiara, no one, neither his enemies or a friend he has rescued before, can recognize him.
"The buck teeth look familiar but the tiara leaves me baffled!"
In "Love at First Height", Chester and A.J. put on a 'tall kid kit' to pass themselves as someone tall enough for the roller coaster. When their fake moustache fell the first time, Timmy's parents were the only people to see it and didn't suspect a thing. The second time, however, was witnessed by smarter adults.
Glaringly obvious in Lilo & Stitch, where everyone notices Stitch isn't a normal dog, but Jumba, a six-foot tall purple guy with four eyes and four fingered hands and Pleakley, who has an exposed antenna, 1 eye, and three fingered hands are able to pass for human with human clothes, combined with glasses and a wig respectively.
People just assume they're birth defects.
Nani does notice the weird shape of Pleakley's head, but assumes it became swollen after Stitch chewed on it. Jumba casually replies "Actually, [Pleakley's] just ugly".
Given the fact that within just a few episodes of the series the experiments and Jumba are running amok doing what they were intended to do, the islanders may have started accepting/adjusting to the fact that there's something weird going on and decided just not to bother.
Gantu's idea of a "disguise" is to claim he's from Samoa. Gantu is fifteen feet tall and an anthropomorphic shark. It works perfectly.
Pet Alien: What's the most paper thin disguise ever? No disguise at all!
Eek! The Cat once featured "famous" performers, the Squishy Bearz, being framed for robbery by four rats wearing a Paper-Thin Disguise. How bad was it? One was just wearing a cardboard box with a smiley face on it and another had a large sock over his head. Done again in the same episode when the Squishy Bearz, on the run from the law, were forced to disguise themselves to avoid detection. Among the costumes worn: A grass skirt and coconut bra combo which really didn't cover the face at all. The people in the local diner didn't recognize them until a news broadcast showed how the Squishy Bearz might look in disguise, showing the exact costumes that they were wearing. Hilarity ensued.
Subverted in El Tigre with Sergio's disguise as his villain alter ego Señor Siniestro. It's actually a very convincing disguise and he's able to fool Manny and Frida. His habit of fawning over Frida is the only thing that could give him away.
Played straight when White Pantera infiltrates a supervillain's tournament. His 'disguise' consists of wearing a black suit instead of his usual white one and calling himself Black Pantera. Nobody is fooled, but play along with it anyway.
In Krypto the Superdog, Krypto's only disguise is a cape with a shield on it. And yet no one, not even the boy's parents, suspected that their dog is an alien dog.
Actually Chris's little sister Sophie figured it right away, but since she's a baby their parents didn't believe.
Underdog arguably does a better job than many on this list, for the way he changes his tone of voice, loses his rhyme, and generally attempts a different persona. But he does nothing to change or hide his face. And from what we see, anthropomorphic dogs are very much in the minority in his hometown.
Actually, at one point during the movie, a man noticed Shoeshine sitting on the stairs and remarked on how much he looked like Underdog.
In The Venture Bros., the original Dr. Venture infiltrates a Super Villain Team-Up dedicated to killing him (who have also kidnapped his son) by pretending to be a Japanese super villain (from the village of Japaninawa). This is done by wearing a wig, fake mustache, a fake nipple on his chin and by pulling his eyes with his fingers so they appear slanted. He makes no attempt to hide his voice or even employ a fake accent. And his cover name, "Dr. Fandragon", is clearly composed of the only two Asian things he could think of. The weaknesses of his costume are all lampshaded by the head villain, who seems to get that 'Dr. Fandragon' isn't really Asian but not that he's Dr. Venture specifically.
Scaramantula: As do we all, my thoroughly Japanese friend who is easily, easily 6'2". Scaramantula: What is that my uncharacteristically hirsute Asian comrade?
Also, Hank's disguise as "Russian Guyovitch", a fake goatee and an outdated Monarch minion costume. Both Sgt. Hatred and Brock are fooled.
Played for laughs in the Wallace & Gromit short film "The Wrong Trousers". There, a villainous penguin dons a disguise, which consists solely of a rubber-glove wig, for his crimes. No one sees through this fiendishly clever ruse, as they all think he is a chicken.
Carl the Evil Cockroach Wizard from Yin Yang Yolives for this trope. On at least one occasion, he actually used it when there was absolutely no reason to. When his brother Herman lampshaded this, he nonchalantly responded "I love to play dress-up." Taking the tone of the show into consideration, there might be some Parental Bonus in that. Yin and Yang are not so good at disguises anyway. One episode Yang put on a mustache and tried to trick Carl. He did fall for that and said "Here, you dropped your mustache... Ah, it's one of my enemies wearing a cheesy disguise!".
And he had it clearly written on a name badge just in case there was a slight chance no one would figure it out.
There's a very slight justification in that this is Tim Scam's first run-in with the girls who had never heard of him. Also the file on him they check has no picture so they don't learn what he looks like until it's too late.
In The Teddy Bears Picnic, two teddy bears are trying to sneak a human girl into the picnic, since she's trying to find her particular teddy bear. The disguise they put together for her consists of a pair of earmuffs, a clown nose, and a line drawn on her face. It manages to fool everyone else at the picnic until she sneezes the earmuffs and nose off.
Johnny Test: To convince a coalition of girls to transport them back home before their parents arrive, Johnny Test disguises himself as a girl. How does he do it? By combing his hair back, putting on lipstick, and wrapping his outer jacket around his waist. The girls are doubtful at first, but he is feminine enough, and they take him, his sisters, and Dukey back to their house. When his parents come home, even his dad is surprised with his "transformation".
And don't forget Dukey. "He's a kid with a rare hair disorder, not a dog." Sometimes he accomplishes this by walking on two legs, and nothing else. He sometimes wears a t-shirt that says Not A Dog.
In one episode of Sushi Pack, Ben needs to talk to the Pack while they're in the middle of a mission, so he dons a disguise to keep their connection a secret. His disguise? A moustache that's not even the same color as his hair. That's it. He didn't even bother taking off the apron from the shop he owns.
In American Dad!, people seem to recognize Roger as an alien only when he's stark naked. If he has so much as a wig on, he's completely inconspicuous despite his obviously non-human body.
In one episode, Roger gets in a hit-and-run accident wearing nothing but a wig, a wifebeater and Kevin Bacon's nose from a disguise kit, and Kevin Bacon gets blamed for it. Even Bacon himself is convinced:
Bacon[crying] I don't remember doing it... but it's clearly ME on the tape!
Steve's friend Toshi knows Roger's an alien, but of course no one understands him.
As does Bob Todd in For Whom the Sleigh Bell Tolls.
Bob Todd: Well, if it ain't an alien in a wig!
Also played with in the episode "Con Heir", when two FBI agents come to the Smiths' home looking for a man who is 6'2", 65 years old, sometimes leaps from a helicopter, has a salty demeanor and wears a turtleneck. Francine thinks they mean Stan's father until she sees the mugshot. In which he has a mustache.
FBI Agent: No mustache? Sorry to waste your time, ma'am.
In the episode "Flirting With Disaster", the Chinese spies infiltrating the C.I.A. are incredibly obvious; they just wear blonde wigs and make Suspiciously Specific Denials while asking for secret nuclear launch codes.
Danny Phantom. This is even commented on in the "Ultimate Enemy" special. Dark Danny has Danny's family and teacher tied up and reveals who he is. He then asks them why they never noticed that "Danny Fenton" and "Danny Phantom" were so similar.
Super Friends (1973) episode "The Androids". The villain Dr. Rebos sends a video message to the Super Friends that shows his real face. A short time later, he talks to both Batman and Superman at close range, with his only disguise being a small server's cap, and both of them completely fail to recognize him.
"You Look Familiar", says Jinx to Cyborg in Teen Titans. Could the young villainess only see past her nemesis' cunning disguise as himself (without cybernetics), she'd undoubtedly fry his wirings on the spot and spare herself a broken heart.
The Teenage Mutant Ninja Turtles could fool anyone by wearing a trenchcoat and fedora, despite their green skin being clearly visible. As soon as they lost the hats, though, it was obvious to all. They did occasionally wear human masks, though.
It wasn't just the turtles. Shredder, Rocksteady, and Bebop could also easily fool anyone, including our heroes. In one episode, April can't see past Shredder's disguise despite it simply being a train conductor's outfit worn over his metal costume... and yet, she found out Bebop and Rocksteady hiding behind a sheet only by catching sight of their shoes.
On Jimmy Two-Shoes, Jimmy managed to pass for Molotov in a spacesuit with nothing but a crudely made stuffed head on a pole.
We see a video recording of customers in an alien sex shop. One of the clients (who is obviously Lrr in a ball cap and sunglasses) tells the clerk he's "just some guy...RULER OF THE PLANETOMICRON PERSEI 8!!"
And when the Decapodians declared war on Earth, and Zap Brannigan couldn't spot their spy, "Hugh Mann", despite suspecting his loyal assistant Kif (Kif seemed to be able to see through the disguise, but didn't say anything, probably because he never gets listened to anyway).
In "The Bird-Bot of Ice-Catraz", Bender is able to disguise himself as a penguin simply by squatting and putting on a tuxedo.
This is played with in the episode which introduces Flexo, the robot who's identical to Bender save for a small metallic "goatee". In a scene, we see what is clearly Flexo trying to pass up as Bender by wearing scarves and other items of clothing and referring to himself almost literally as "Not Flexo, but Bender". Later is revealed he was actually Bender all along and was wearing that clothing because of fashion sense.
When Fry and Leela visit a robot planet, all they need to blend in perfectly is to wear metal containers and pots.
Cubert Dwight and Tinny Tim were able to steal from Fry and Bender's apartment in plain sight of Fry by wearing crudely drawn Bender masks... all three of them at the same time.
Phineas and Ferb: Perry the Platypus frequently employs this trope during missions to deceive his arch-nemesis Dr. Doofenshmirtz, who is completely incapable of recognizing Perry when he's not wearing his secret agent hat.
Another time, Perry disguises himself from Linda by putting on a pair of fake glasses and nose. Unsurprisingly, Dr. Doofenshmirtz is also fooled by it.
The best example has to be when he disguised himself as a plumber with a hat and a tool-belt. When he confronted Doof, this conversation followed.
Doofenshmirtz: What kind of plumber are you?
Perry: *removes hat*
Doofenshmirtz: A platypus plumber?
Perry: *puts on fedora*
Doofenshmirtz: Perry the platypus plumber?
Perry: *drops belt*
Doofenshmirtz: *gasp* PERRY THE PLATYPUS!!
In one episode, Perry gets out of Doof's trap simply by removing his hat. Doof immediately releases him, thinking he's a perfectly ordinary, innocent platypus who was put there by Perry the Platypus. Makes you wonder why Perry doesn't do that every time. Maybe he just likes a challenge.
Not to mention in the episode "Not Phineas & Ferb" Baljeet & Buford dress up as the titular duo to fool Irving's older brother Albert, with their disguises consisting of P&F's regular clothes and some very unconvincing masks (resulting in Buford having, as Irving later states "eyes in his mouth"). Ironically, Albert is the only one fooled by them.
Baljeet:(pretending to be Phineas) I know what we are doing today. Buford: And I'm British and I don't talk much.
In "Phineas and Ferb Get Busted," Candace disguises herself as TV personality Morty Williams.
Even her own parents are fooled. When they put the same Paper-Thin Disguise on a cactus, everyone thinks it's Morty Williams. When the drill sergeant shows the guards that it's just a disguise by putting it on in front of them,they think he's Morty Williams.
Hilariously subverted in League of Super Evil, where the gang are attempting to gain access to a prestigious restaurant. A man enters the lobby who is quite clearly just all four members of LOSE stuffed inside a trenchcoat and matching hat with a pair of sunglasses and a false moustache on. He is allowed through without incident, and is immediately followed by an IDENTICAL man, whom it turns out IS the gang in a trenchcoat. After the disguise has failed epicly and LOSE have been thrown out into the bins, Red Menace remarks "Maybe we should have gone in before the other guy."
In the King of the Hill episode where Dale is a Bounty Hunter, when he disguises himself as a flower delivery man to attempt to gain entry into the fugitives house, he doesn't even bother taking off his "Bounty Hunter" hat. Unfortunately for Dale, this works about as well as you would expect. To be fair, he never takes hat off unless forced to, since he is self-conscious about his bald spot.
In the episode "Revenge of the Dark Stone" of Princess Gwenevere and the Jewel Riders, the evil Lady Kale supposedly dresses as her good twin Queen Anya to infiltrate her palace while wearing a burqa-like robe. It's a strange disguise, as Anya is never seen wearing anything like that, her eyes are still of a different color and her voice is still different too, so presumably she didn't just change her hair color in order to smuggle her two Dweasel creatures with her under the robe. Needless to say, such disguise worked perfectly.
Newton, of Ned's Newt, is a 6-foot tall shapeshifting blue humanoid newt. But as long as he's got some human clothes on, nobody notices. Of course, pretty much all the adults in the setting are more or less idiots.
When in his civilian identity, Robin in Young Justice needs to be in disguise (apparently it's something Batman insists on). All he does is pull on a pair of sunglasses.
In Robin's defense, the team does not have any contact with Dick Grayson unless Artemis goes to Gotham Academy.
A better example of this trope would be Conner. He doesn't wear a mask or any costume at all, but so long as he isn't wearing a Superman t-shirt, no one recognizes him to be Superboy.
Its even worse than that; Connor refuses to wear anything but black super-man T-shirts, even in his civilian identity. Presumably the only reason why his classmates haven't worked it out yet is that he's part of a covert OP team that doesn't get a lot of media attention.
Brain from Inspector Gadget is able to fool Gadget sometimes just by wearing a hat, glasses, and fake mustache and he never recognizes him no matter how bad his disguise is.
From Star Wars: The Clone Wars: Despite supposedly being the bestBounty Hunter in the galaxy after the late Jango Fett, Cad Bane's Jedi disguise is pretty pathetic. You'd think that a guy like him would put a little more effort into it.
Parodied and inverted in Garfield and Friends, with Orson wearing nothing but a moustache and costume posing as the Rooster Ranger to play a trick on Roy. Roy immediately recognized it as "Orson in a pathetic disguise", but when Orson fell into his mudhole Orson came up to investigate. It turned out that the Rooster Ranger was actually Lanolin in costume.
In another episode, Roy was hosting a game show where the audience had to call in and guess the mystery guest. The guest was Garfield wearing a Lone Ranger mask. Orson complained that anybody could clearly see who it was, but nobody got it right, not even Jon.
Fluttershy uses a large hat and sunglasses to go unnoticed during her fashion model career, which would have been more convincing if her canary-yellow body and distinctive cutie mark were also concealed.
Inverted in "Party of One." Pinkie Pie disguises herself as a block of hay. Wearing a trenchcoat and fedora. And Groucho glasses. Despite the over-the-top silliness, it could be a effective disguise, if everyone didn't already know Pinkie Pie would be the only one crazy enough to wear that in the first place.
In "Dragon Quest", Rarity disguises herself, Rainbow Dash, and Twilight Sparkle in a silly-looking dragon costume. This manages to fool the dragons, largely because there's an actual dragon among their number that is nearly identical to the costume.
In a Sylvester the Cat and Tweety Bird cartoon, Sylvester attempts to disguise himself as a monkey in order to infiltrate Tweety's apartment. Initially it seems as though his disguise was actually working, but then he lifts his hat up and she whacks him in the head, with her also saying "Did you really think I would be fooled by that disguise?", making this a subversion similar to the Mr. Burns example.
Inverted on The Cleveland Show in the episode where Roberta dons a Fat Suit. It's a very convincing disguise and almost everyone is fooled, but somehow Cleveland, Donna, and Rallo see through it.
Even more so with Mater's disguise as Ivan in Cars 2.
In Johnny Bravo, one episode features a shark walking on its tail fin wearing a RichardNixon Mask at the tip of its snout. Although a scarce few are suspicious, most are fooled by the disguise.
Another episode featured a werewolf girl, who was perfectly disguised by a piece of cloth the size of a napkin over her the lower half of her face.
In every episode of the British children's animated series Poppy Cat, the badger Egbert appears in the characters' adventures as a villain wearing a paper-thin disguise. The catch, however, is that unlike most instances of this trope, the characters always recognize him who he is and even call him "Egbert," but he insists "I am not Egbert, I am such-and-such character."
In the "Christmas: Impossible" segment of Mickey's Twice Upon a Christmas, Huey, Dewey, and Louie mosey around Santa's workshop wearing their usual monochrome shirts plus green hats. Their doubts of success disappear the moment an elf addresses one as "fellow elf."
The Tom and Jerry short "Puttin' on the Dog'' has Tom disguising himself as a dog to infiltrate a dog pound that Jerry is hiding in, with nothing but a yellow dog mask. The short's gags revolve around Tom trying to keep track of his mask. At one point, Jerry hands a suspicious Spike this message: "Yes stupid, it's a cat."
In Get Muggsy!, the title character's friends (an opossum, raccoon and spider) need only stuff sticks of white gum in their mouth to fool others into thinking that they are beavers.
In the episode "From here to Ed" in Ed, Edd n Eddy, the Eds manage to sneak past Kevin by disguising themselves as Jonny. Which means all three Eds are crammed into a gigantic papier-mâché sphere vaguely shaped like Jonny's head, with the eyes cut out and all three Eds plainly visible inside and an imitation Plank glued to the side. Kevin doesn't seem to notice, saying hi to "Jonny" and muttering "What a freak" when "he" hits the fence and falls over it.
In the episode "Laugh Ed Laugh", due to an epidemic, there are no kids for Eddy to scam causing him to eventually go completely insane. Ed and Edd attempt to capture him for his own safety and approach him by wearing badly drawn masks of Jonny and Plank. Ironically Eddy falls for the disguises even when Ed's mask FALLS OFF! Eddy thinking "Jonny's" face has fallen of assures "Jonny" that he will get him a new one.
Eddy: Hi Plank! [Ed is wearing a Jonny mask, and Edd is disguised as Plank.] Hi Jonny! I'd invite you in, but I just shampooed the rugs! [Ed's mask falls off which causes Edd to Face Palm] Ed: Oops. Eddy: Jonny. You dropped your face... I'll get you a new one!
In the Rugrats episode "Angelica's Twin", Angelica pretends to have a twin sister to get two toys instead of one. Angelica becomes "Balina" by tying her hair in a knot and rolling up her sleeves. Tommy tells Angelica to stop pretending but falls for it once she plays dumb. When Betty asks Didi if she is really going to buy two toys, Didi answers that she shouldn't stifle Angelica's creativity. The babies end up liking Balina more than Angelica.
In He-Man and the Masters of the Universe (1983), He-Man is basically Prince Adam with different clothes and... that's it. Same face, same haircut, same body, with a tan; his voice was deeper, but he spoke in nearly the same speech patterns.note He called the king and queen by their royal instead of parental titles. Likewise, Kringer becomes Battlecat by... putting some dark red armor on.
His sister was pretty much the same. She-Ra's only real difference from Alura was a change of clothing that didn't hide her face at all, and seeing as Alura was an Action Girl in her own right who used to work for Hordak before her Heel-Face Turn (as a moderately high-ranking officer, no less), you got the idea that the Horde was kind of dumb.
Averted in one episode, where Kobra Khan disguises himself as a human: there is no resemblances at all, except in his speech... and Orko is still able to see through it.
Hurricanes: In one episode, Napper's younger brother Nigel joined a gang of hooligans and Stavros Garkos decided to use them to convince the World Soccer Association (that series' version of FIFA) to shut down the Hispanola Hurricanes' stadium. When Nigel saw the hooligans' true colors, he agreed to spy on them. When trying to collect data from Nigel, Napper approached him wearing sunglasses and a fake mustache as a disguise to avoid being recognized by the hooligans. The only hooligan to see Napper in that disguise saw through it.
Averted on Doug when Skeeter tried to go to the Honker Burger in disguise after running away from home. Everyone recognized him right away.
The Beavis And Butthead episode "Pool Toys" has the duo wear nerd glasses to try to fool Tom Anderson into getting them to build his swimming pool. Were it not for Anderson's poor eye sight, this plan probably wouldn't have worked.
Sheep in the Big City uses various poor disguises. Sheep uses them to hide from the Secret Military Organization. General Specific and his men use them to sneak toward sheep.
Sometimes, the military uses less than disguise. Thus the arrow sign that says "Top Secret Military Base" and "Please look the other way". The secret helicopters bear the label, "Please Ignore".
In Rocko's Modern Life Filbert recalls when he first met Heffer when he began a job giving away free samples at the grocery store. His boss warned him that Heffer was a master of disguise. As a result, the ever paranoid Filbert didn't trust anyone wanting to try the free samples, and yet still kept trusting Heffer, who's disguise consisted of a paper bag with a smiley face painted on it.
In "An Elk for Heffer", Heffer manages to sneak into an elks-only club by sticking a pair of branches over his regular horns.
Heffer: I am an elk. I have antlers. Bouncer: You want a prize?
On Goof Troop in order to convince Pete that he doesn't need any more children, PJ disguises himself as a baby. PJ is a very overweight eleven-year-old, and besides that is Pete's son, whose apparent absence was not remotely explained until Max says he's at the store several minutes later, so Pete should have noticed (he didn't). Dramatic Irony is Played for Laughs here, with Pete delivering the lines, "Aww, kind of reminds me of PJ back when he was cute!" and "PJ was never this bad!" The former of the lines results in PJ biting Pete, with his fully developed adolescent teeth, and Pete still doesn't notice. He does, however, comment on how absurdly big he is. At least PJ's acting was better than it usually is.
Umi Car's Tiger Disguise and Bot's Poodle Disguise from Team Umizoomi
And it works!
Alluded to in the Home Movies episode "Camp." Coach McGuirk is on the run from cultists, and among the long list of things he asks from the people he's staying with is a fake mustache. The thing is, in the time since the cultists last saw him, he's grown a full beard. In effect, he wants a "paper-thinner" disguise than the one he already has.
Happens all the time in The Houndcats, especially given the size of Puttypuss, the "cat of a thousand faces."
Played with in "Adopt-a-Con", where Tuskernini is able to fool others when dressed as Megavolt and Bushroot, despite being much more overweight than them. Darkwing Duck isn't fooled by the Megavolt disguise (and it's unclear if the tied-up guard is), while DW, Launchpad, and Gosylyn all know in advance that he's going to be disguised as Bushroot. However, those unaware don't know that he's really Tuskernini. The judge only finds out after he sees the flower pot used as hair fall off.
Whenever Quackerjack wears a disguise (such as a psychologist in "Days of Blunder" or a surgeon in "Stressed to Kill") he wears his signature jester mask, which he is rarely seen without. One would think he'd be less likely to be recognized without it.
Whenever Launchpad dresses as Darkwing others get fooled.
DrawnTogether has this in "Mexican't Buy Me Love" where Ling Ling plays a verrrry convincing fighting rooster...with nothing more than a fake beak.
In the Adventure Time episode "Her Parents", Jake disguises himself as a rainicorn by shape-shifting himself in order to have a long body and a horn, and painting himself in condiments. He's utterly baffled when Lady Rainicorn's parents fall for his disguise.