Disguises haunted Mary Marvel's entire career. A change of slacks or a well-placed hat would throw her right off your trail. If you punched a puppy with your left hand and waved to Mary Marvel with your other, she'd apologize and ask you if you saw anyone run by left-handedly. She died a virgin because every time one of her beaus changed clothes she mistook it for a first date.
Doofenshmirtz: A banjo-playing platypus?
Perry dons his hat
Doofenshmirtz: PERRY the banjo-playing platypus?!
Mr. Furious: That's because Lance Hunt is Captain Amazing.
Blue Raja: Oh here we go...
Shoveler: Oh, don't start that again! Lance Hunt wears glasses. Captain Amazing doesn't wear glasses.
Mr. Furious: He takes them off when he transforms.
Shoveler: That doesn't make any sense. He wouldn't be able to see!
— Mystery Men
Banjo: I'm Banjo the Stony. Can I come in and play?
Officer Unogopaz: Hmm... I don't know. That backpack looks kinda familiar...
Kazooie: Are you saying we're a bear and a bird in an elaborate disguise, trying to cheat our way in?
Officer Unogopaz: Yep, it's pretty obvious.
"You wear a disguise
to look like human
but you're not a man
You're a Chicken, Boo"
(After having fallen for one of the Beagle Boys disguised as a woman)
"Great Flaming Catfish Whiskers! The Beagle Boys! The moustache shoulda tipped me off! I need to get out more!''"
— Scrooge McDuck, Master of the Mississippi
Darkwing: Hold the phone. You're not Megavolt; you're Tuskerninni, in a really bad Megavolt disguise.
Tuskerninni: I am not Tuskerninni, and this is an excellent disguise!
— Darkwing Duck, "Adopt-a-Con"
"Aw, gee! These disguises don't fool nobody!"
— Bebop, Teenage Mutant Ninja Turtles
(Steve appears, wearing a Shy Guy mask.)
Steve: Hi guys! Can I join you guys? Huh? Huh?
Shy Guy: Hmmm... you look about right. What's your name?
Steve: Steve... Oh no, I mean Shy Guy!
Shy Guy: Well then... welcome, brother!
—Bowser's Kingdom episode 2
My God! You mean the blonde woman with the German accent is actually the blonde woman with the German accent?
"Villains always fall for cheesy disguises."
— Bugs Bunny (briefly poorly disguised as Taz), explaining to Buster and Babs a few basic facts about being a cartoon character, Tiny Toon Adventures
(Antimony approaches door, wearing a headband with attached antennae.)
Antimony: Hello. I would like to enter, please.
Doorbot: Robots onl... what's that on your head?
Antimony: These are my antennas, because I am clearly a robot.
Doorbot: Oh! Well... it's true that some robots have antennas... hmm...
Antimony: Also, robots never lie.
Doorbot: Hey, you're right! Come on in, friends!
The three escapees continued making progress, slowed only a few times when they were spotted by ninjas, all of whom held brief discussions of questionable logical validity before agreeing that the three couldn't possibly be who they very obviously were.
"There, you see? Count Olaf has one eyebrow. Coach Gengis has a turban. They look nothing alike."
— Vice Principal Nero, The Austere Academy
Bart: There's something different about you.
Homer's German Doppelganger: I am a new tie vearink.
Bart: Oh yeah.