Raven: (disgusted) Don't smell it? I can see it!
Cyborg: (horrified) It's thick enough to cut through! (snips off a piece of the stench, which falls on the floor)
Smells are even colour coded. Bad smells are usually green, yellow, or brown, and are sometimes accompanied by flies, while nice smells are usually pink, blue or possibly brown if the scent is coming from food. Burnt smells are given a charcoal grey colour, while coffee is given a trail of steam.
The Rule of Perception is the whole reason for this trope's existence. If the audience isn't aware of something, it doesn't exist. Therefore in order for a smell to exist, it has to be able to be seen or heard by the audience. Creators use this trope as a non-intrusive way of informing the viewers, as it doesn't interrupt flow of the scene like having characters break of from a conversation to comment on it would.
Used in animation much more often than it is used in other media, as in Real Life this usually doesn't happen, and would disrupt the immersion of the audience if it was used in, say, a Live Action Film. In other media, viewers are more likely to be informed of the smell by people complaining about it.
This is a Sub-Trope of Editorial Synaesthesia. May be caused by a Smelly Skunk, Fartillery, Wilting Odor or Toilet Humour. Compare Tastes Like Purple. Follow Your Nose is when an enticing smell is not only visible but strong enough to carry a character along.
- In the "Dancer" commercial for Kellogg's Pop-Tarts, the pastries in the toaster give off a visible vapour. Ten percent of the vapour is strawberries, representing the ten percent fruit in the filling.
- The Poo~Pourri adverts represent the smell of the poo with brown skulls and spirals, and the nice smell of the Poo~Pourri with leaves and flowers.
- One arc in Mononoke depicted smell with colours, whereas almost everything else was Deliberately Monochrome.
- In One Piece, Usopp's Egg Star involves him firing rotten eggs from his slingshot and releases a green vapour.
- The character Honey in Ouran High School Host Club always has floating flowers around him.
- Pleasant Goat and Big Big Wolf: In episode 173, the wolves notice a nice smell coming from the goats. The smell is visible as a trail of white steam.
- In Over the Hedge, Stella the skunk fills a house with green gas. Conveniently, her boyfriend, a Persian cat called Tiger, can't smell it.
- In the film version of Anonymous Rex scents carried by particular dinosaurs were conveyed vivid visual depictions of the scent items. For example, one dinosaur smells of peaches and cream and, images of brightly lit peach slices falling into cream appear on the screen.
- Averted by Polyester, in which audience members were given "Smell-O-Rama" scratch and sniff cards.
- Captain Angua, a member of the Ankh-Morpork City Watch and their token werewolf, is described as perceiving the world primarily through scent rather than sight while in wolf form. The text describes it in terms of ribbons and clouds of brilliant colors, far more vivid than anything she's able to actually see as a human. She's even able to track criminals by their Fluorescent Footprints.
- Granny Weatherwax experiences the sensations of animals she's Borrowed in a similar way.
- Stephen King's novel The Eyes of the Dragon has a passage written from a dog's point of view, in which scents are described as lines of various colours.
- Scents are described in a similar way for Wolpertings in Rumo & His Miraculous Adventures.
- In Children Of God, an alien who has a far better sense of smell than a human is tracking a missing friend. She "sees" his scent as points of light along the trail.
- In The Pigeon Needs a Bath, one of the ways you can tell is the visible stink lines depicted on him on the pages where he insists he doesn't have a smell.
Pigeon: What smell? (sniffing himself) I don't smell anything! And if I do— it' s very normal smell. For a pigeon.
- Daredevil (2015): Matt Murdock is blind as the result of a childhood accident, but his other senses are greatly heightened, to the point where he describes to Claire Temple that the combination of smell, sound, and air vibrations are akin to 'seeing' a world on fire, per the title of that episode.
- CSI has Bloodhound-O-Vision, which displays the visible world in black and white, while scents appear as colourful patches.
- In South Park: The Stick of Truth, the fart icon is a green cloud, although your actual farts have no colour. Additionally, people inflicted with the Gross Out effect (similar to poison) and people you have farted on outside of battle will be surrounded by green mist.
- Leisure Suit Larry 7: Love for Sail! partially subverts this, as it comes with Scratch and Sniff cards, allowing the player to actually smell what is happening in the game. However, Larry still emits yellow fumes when he farts.
- Super Paper Mario:
- Averted when Merlee has a fly buzzing around her after hiding in a toilet, indicating that she smelled, this was not visible in any other way. This was probably to make it harder for the player to tell her apart from the shapeshifter Mimi.
- However, this is played straight with O'Chunks, whose farts are yellow-green.
- In Far Cry Instincts smell is shown as a coloured aura and trail.
- In Discworld Noir, while playing as a werewolf you can indeed see scents as patches of coloured mist. They can be 'collected' like items and you have to match the patterns to ones you've encountered before to track where characters have been.
- In Pokémon Mystery Dungeon: Explorers, Skuntank and Koffing's stink is portrayed visually as a purple cloud.
- The Legend of Zelda:
- Sveta's Track Psynergy in Golden Sun: Dark Dawn allows her to find scent trails, which appear as a streak of white vapour close to the ground.
- The Sims:
- In Boogerman, the eponymous protagonist uses Fartillery as his main weapon; his farts are visible with a green colour.
- In Samurai Shodown Earthquake in the first 2 games farts on the enemy, shown as a purple cloud.
- In Dog's Life, Jake can sniff out smells. Each smell has its own colour.
- In Level 2 of Sheep, Dog 'n' Wolf, Ralph uses a bottle of Lady Sheep the perfume for lady sheep that no male sheep can resist by the means of using a fan to propel its pink cloud of odor in order to entice a sheep.
- In Fizzball hitting a skunk before the Fizzball is large enough to contain it or destroying a toxic waste barrel by hitting it too many times produces a green cloud.
- Used several times in My Little Pony: Friendship Is Magic:
- In Dragonshy, the dragon's smelly breath is green.
- In Winter Wrap Up, Twilight is sprayed by skunks after being chased by bees into the burrow they were hibernating in. The skunks leave a trail of green mist behind them, and in the next scene, Twilight is also surrounded by a green cloud.
- In Baby Cakes, Pound Cake and Pumpkin Cake's dirty nappies emit a green vapour.
- In Tinga Tinga Tales, Skunk initially produced a nice smell, represented by pink. However, Baboon tricked him into eating a Smelly Fruit, which made him produce nasty smells instead. These were represented by green.
- Looney Tunes and Merrie Melodies:
- Scents were often depicted as a ribbon which snaked through the air toward a character, and would even lift the character into the air and carry them toward the source of the smell.
- Other times, they depicted it as a coloured aura or mist instead. Notably, Pepe Le Pew's body odour was a murky green fog, which other characters only smelt on visibly inhaling it. Similarly perfumes were pink and food was blue-grey.
- In Avatar: The Last Airbender, the vision of an animal which uses its sense of smell to 'see' is represented in streams of different colours, each representing a different scent.
- In Camp Lazlo other campers were unwilling to take a bath after getting extremely dirty. So they hide from Lazlo behind a bush. Unfortunately for them, Lazlo saw their stink lines above the bush.
- One of the Classic Disney Shorts is "R'coonDawg", in which Pluto's ability to track down prey is shown by having whatever he was smelling appear before him, with the narrator explaining that it was as if he could see with his nose. The raccoon he's chasing exploits this by using a fish, a frog and a horseshoe to lose his scent, causing Pluto to see bizarre raccoon/fish/frog/horse hybrids.
- Lampshaded in the Phineas and Ferb episode "Misperceived Monotreme", when Major Monogram sees Carl the intern eating a peanut butter, banana, and sardine sandwich (complete with stink lines), and claims "I can see the smell from here!"
- In the The Transformers episode "Starscream's Ghost", a visible stench from alien food wafts towards Octane's nose and he audibly sniffs it.
- Spongebob Squarepants:
- The scent of cooking Krabby Patties are given a smoky white.
- Rancid smells, like the time Spongebob ate a "sundae", are given a rancid green colour that eminates through the air around Bikini Bottom.
- Then there's the Perfume Department, where the chokingly fragrant smells are pink and light blue.
- Whenever a character is said to have bad breath, green lines emanate from their mouth.
- In "Let's Play Ecologists", Kaeloo gives Stumpy a piece of stinky cheese to throw away that has squiggly lines over it to represent its odor.
- On ToddWorld, in "Todd Builds a Fort," Benny digs up a buried cream doodle from 1969 which he says is "still fresh." Todd grabs and throws it away, saying that it isn't, and one of the ways you can tell is that it has visible stink lines emanating from it. The same is true in "Pickle's Smelly Socks" in which Pickle has a problem with terrible sock odor, but nobody wants to tell him.
- In Arthur's Perfect Christmas, to show his family's tradition of Sankta Lucia, George brings a tin of dried and boiled Swedish fish called lutefisk to class and offers it to his friends. It has a definitely visible odor and naturally everyone passes it around as rapidly as they can, except for Buster, who tosses a piece into his mouth, says "Yum! Not bad," and goes for another while George watches happily.
- In "Brontosaurus Breath" on Doc McStuffins, Bronty's bad breath due to a bit of salami stuck in his teeth is represented as a sickly green odor.
- My Friends Tigger & Pooh:
- In "Beaver Gets Skunked," Skunk's stinky spray that upsets Beaver so much is depicted as a noxious cloud of green odor.
- Similarly, in "Skunks Non-scents," all of the stinky scents that the Super Sleuths try out for Skunk, as well as the stench that Skunk is eventually able to make are depicted as stinky green odors.
- The Crumpets uses yellow-green clouds for bad smells, like from Granny's onion crisps, the bath-avoiding King in "Amnesia", and the stench inside the van in "Road Stories".
- In "Bathtime for Boomer" from Kate & Mim-Mim, Boomer badly needs a bath, as clearly indicated by the green stink lines coming off of him, though these aren't shown after around the beginning of the episode, apparently given that we're supposed to take it for granted that he's still stinky.
- Die Sendung mit der Maus: In a Maus spot, she follows the scent of...cheese?...sausage?...oh bother, it's an old boot.
- Justified in The Magic School Bus episode "Makes a Stink". When Ms. Frizzle is teaching her class all about smells and how they work, she offers them Smell-a-visors that makes odor molecules completely visible, and color coded depending on the source of the smell, like red for roses or off-white for gym socks.
- Esme & Roy:
- Tillie gets one in "Monster Trucks" after getting very dirty and needing a bath.
Roy: Monster Fact 5976: When Plink monsters get dirty, they get really stinky, like majorly monster stinky.
- The "scratch and stink" stickers that Tillie gets in "Supermarket Match" for winning the game of Supermarket Match have this to show their stinky odor.
- Tillie gets one in "Monster Trucks" after getting very dirty and needing a bath.
- The giant fart monster in The Powerpuff Girls episode "Reeking Havoc" is a sentient brown cloud created from the collective farts of everyone who tried Professor Utonium's Chemical X-laced chili. Blossom defeats it with a giant lit match.
- Beast Boy's disgusting odor is visible as a green fog around him on Teen Titans Go! episode "Hot Garbage". When he says he doesn't smell it, Raven incredulously responds that she can see it, while Cyborg adds that it's thick enough for him to literally cut a wisp off of.