A Rule of Perception-based Retcon in which something the characters are fooled by that should obviously be fake from its physical appearance alone isn't obvious to the audience because the scenes before its true nature is revealed portray it as the way the characters perceive it, at which point it suddenly changes to show its true nature. Essentially, rather than have someone's Paper-Thin Disguise be obvious to the audience but not the characters the whole way through, their disguise is foolproof to both parties until the characters find out they've been tricked, at which point it changes for no reason so that it looks appropiately shoddy.
Note that magic, visual tricks, or a masquerade suddenly falling apart (see Game Face, Glamour Failure, The Shadow Knows, Missing Reflection and The Mirror Shows Your True Self) once the characters come to their realization are not involved. Rather, the disguise or object should logically appear to be obviously-fake the whole way through, but the visuals portray it as if it were the real deal so that both the characters and audience will be fooled until The Reveal when the visuals change for no discernible reason. In Watsonian versus Doylist terms, while the Doylist explanation for why its appearance changed is that the audience needed to be fooled just like the characters, there is no Watsonian explanation for why the audience saw it the way they did, at least not for stories that don't have an Unreliable Narrator who describes and visualizes absolutely everything as it's happening with no alternate perspectives. There might be a minor Rewatch Bonus revolving around hints in the behavior of the person or object, but visually, there's unlikely to be anything.
Compare Paper-Thin Disguise where an obviously-fake disguise is obvious to the audience the entire time rather than suddenly changing once the truth is revealed. Also compare Tomato Surprise. Through the Eyes of Madness would occur if the audience and characters see the fake thing as real because the character serving as our viewpoint is crazy, though this trope would be more "Through the Eyes of the Deceived" until they find out the truth and the perception changes. An Ass Pull or Shocking Swerve can occur for extreme examples, but not always.
Due to the bait-and-switch nature of this trope and how heavily it relies on the audience going in blind, expect spoilers.
- Gravestone of Daisuke Jigen: The Big Bad of the film successfully manages to assassinate his mark, Jigen, with a well-placed sniper shot to the head at the end of Part 1. In Part 2, however, the bullet is revealed in a flashback to have barely missed Jigen's head, giving him the opportunity to fake his death by detonating a small device filled with blood placed on his forehead. Here, he lifts up his Cool Hat up to reveal the device, but prior to the reveal he does no such thing, at least from the assassin's point of view.
- Mobile Fighter G Gundam: Among the show's Word of God-admitted tendency to defy logic for the sake of being awesome is a trend of Death Army troops managing to perfectly imitate any mobile fighter by copying a few of its armaments and adding a new headdress. Despite the individual units never adjusting their color schemes, face, or anything from the chest down (and even then, the only torso changes to expect are a new chestplate or backpack), both the characters and audience will see them as an exact duplicate of the imitated mobile fighter until the truth is revealed and it becomes obvious that they are just a Death Army trooper with two or three new parts slapped on.
- Shin Mazinger: The Gamia sisters get hit with this once revealed as deadly gynoid assassins. They never show any robotic attributes during their Furo Scene, best seen when one of them is briefly shown fully nude in a few frames shortly after they jump into action and start whipping their razor-sharp pigtails around (though she was about as detailed as a Barbie doll at that moment). After some exposition fully explains them to be gynoids all along, they suddenly appear more robotic than before, their bodies gaining doll-like joints.
- In Transformers: Go!, Tobio pulls a Wounded Gazelle Gambit to steal Kotaro Fuma's Legendisc and instead grabs an old plate. The shots before he finds out that it's a plate show him grabbing a silver disc and then holding up an orange circle for both of the Legendisc's sides, neither of which resemble the dull gray plate.
- Suikakasen has Seiga summon a copy of herself to chop up its own arm to emphasize a Humans Are Bastards point she's making to Yoshika. After finishing talking, she reveals that (among other things) the copy is just a puppet, and its elbows and wrists gain obvious doll joints not visible in the previous shots of its seemingly-organic arms.
- Played for laughs in the first Austin Powers film. Austin is in a nightclub when he suddenly screams that an attractive woman is a man. When we cut back to "her", she's suddenly and very obviously a burly, unshaven stunt artist in drag, who attacks Austin.
- James Bond has at least two cases in the cold open, From Russia with Love (after Red Grant strangles "Bond" and it's revealed to be a SPECTRE training montage, the corpse turns out to have a James Bond mask) and Thunderball (after Bond punches the widow, who had been played by a woman that far, she becomes a man in drag - the supposedly deceased husband).
- In one chapter of Robert Sheckley's Dimension of Miracles, Carmody encounters three humans, has a conversation with them and follows them to their ship. Only then does he notice they are nothing more than cylinders of flesh with some features painted upon them, and the ship is the mouth of a predator attempting to eat him. Before this, they are described as walking, blushing, exchanging looks... but once Carmody looks carefully, they have no parts to do any of these things. Just three fingers.
- In one Key & Peele sketch, several friends having a party panic when they see what appears to be an incoming drive-by, when it's really an acquaintance pulling a prank. When Peele's character first shows up, he's in a black jacket and fancy car and drawing a pistol, but when his prank is revealed, the jacket is now made out of a garbage bag, the pistol is made of licorice, and the car is just one painted wood panel.
- In Dungeons & Dragons illusion spells look completely real (but may not seem real to all five senses. It depends on the spell) unless someone interacting with them succeeds at their saving throw to disbelieve the illusion, at which point they can still see the illusion but it looks like an phantasmal outline of the object or creature it's meant to look like.
- In Octodad, Chef Fujimoto dresses up a mannequin with a T-shirt, fruit, and meat to trick Octodad into thinking it's his wife. The mannequin looks like a person until the moment he touches it.
- In Team Fortress 2, the spies appear with a literal Paper-Thin Disguise consisting of a mask of whoever they're disguised as to their own team. The other team just sees the character model of their disguise, but see the spy normally if they force them to lose their disguise or kill them (which leaves the mask on the dead spy).
- Adventure Time: In "Red Starved", Finn starts searching for a red object for Marceline to suck the color out of, and his search leads him to a creature with a large ruby. Finn requests the ruby, which the creature insists is an emerald before giving it to him. Once Finn returns to Marceline and Jake, Jake also tells Finn that the ruby is an emerald. After Jake explains that Finn must be a little colorblind, the "ruby" changes to green to indicate that it is indeed an emerald.
- American Dad!: In one episode, Roger reveals that for each member of the Smith family, he has a disguise that they cannot see through. To demonstrate this, we cut to a flashback of Steve kissing a girl. At first she looks like a normal teenaged girl. However, as Steve goes in to kiss her, it becomes clear she's just Roger in a wig and makeup.
- Exaggerated in one episode of Dave the Barbarian where Chuckles created an evil clockwork duplicate of Dave that looks identical to the original and Fang and Uncle Ozwidge are too dumb to figure out which is the fake even though the imposter acts extremely out of character. They ask Candy which one is the fake and she points out that the fake has a giant and incredibly obvious windup key in its back and is surprised that they didn't noticed it before. The windup key and the clicking sounds that it makes only become visible and audible to the audience after she points it out. Additionally, before this is revealed the fake Dave is seen sneaking with his back against a wall which should not have been possible if the key was there the whole time.
- The Fairly OddParents: "Wish Fixers" has Jorgen on the Pixies' side until Cosmo bumps into him, at which point it is revealed that he is actually a robot copy with a wire sticking out to plug into the wall. No such plug or wire is visible until "Jorgen's" true nature is revealed.
- Mulan is drawn with several slight differences when disguised as a man, to aid the plausibility of her appearance (for example, she has eyelashes only when she's not in disguise). The shot in which her imposture is exposed as she sits up in bed has her drawn with the variations for her feminine appearance, even though all that has changed since the last scene is that her secret is known.
- Downplayed in Scooby-Doo! and the Monster of Mexico. The "skeleton" operating a The Wizard of Oz-style holographic ghost is clearly a man in a costume from the beginning. What's not clear is who's in the costume, until he gets unmasked. After we find out it's the fat Mr. Smiley, his costumed body-shape goes from being rather thin to being realistically fat, despite him wearing the costume the entire time.
- The Simpsons: "The Springfield Files" has Homer see a man engulfed in green light that he assumes to be an alien, and eventually manages to convince the town to come to the same location another Friday night. Lisa and Smithers reveal the alien to be Mr. Burns after getting special treatments every Friday and glowing green from the power plant's radiation. At this point, his green glow becomes much fainter so that it doesn't engulf his entire body and makes it clear that he is just Mr. Burns, and the flashback showing him getting his treatments follows suit.
- South Park: In-Universe in The Succubus during the Nessie stories Chef's dad tells. All of them are about Nessie bugging Chef's parents for "tree fiddy", and one of them involves the monster dressing up as a Girl Scout selling cookies. Chef's parents don't recognize him... until he asks for tree fiddy.
Chef's Dad: Well it was about that time that I noticed this "Girl Scout" was about eight stories tall and was a crustacean from the Paleozoic Era.
- SpongeBob SquarePants:
- The plot of "Penny Foolish'' relies on Mr. Krabs and the audience both seeing a piece of green gum as a brown penny until SpongeBob shows Mr. Krabs what he really picked up off the sidewalk that day.
- "One Coarse Meal" has Plankton be terrorized by Pearl until the second half when it is revealed that "Pearl" is really Mr. Krabs in a costume with visible seams and patches that can't disguise the shape of his body from the head down. Before this, his costume was a one-to-one recreation of his daughter.
- Xiaolin Showdown: Inverted in the episode "Chameleon". Jack kidnaps Kimiko and replaces her with the Chameleon-bot, which mimics her appearance. When the bot appears around Kimiko's friends, it has a clearly robotic appearance and tone of voice. However, when the real Kimiko shows up next to it, the bot now looks and sounds identical to her.