Disgusting Public Toilet

Don't worry, we're not going to show you what's inside.

"I fantasize about a massive pristine convenience. Brilliant gold taps, virginal white marble, a seat carved from ebony, a cistern full of Chanel no.5, and a flunky handing me pieces of raw silk toilet roll. But under the circumstances I'll settle for anywhere."

—Mark Renton, Trainspotting

When Potty Emergency strikes, one is forced to find a place to go, fast. Looking around, you notice a public toilet. You sigh of relief, until you open the door...

This place is littered with Bathroom Stall Graffiti, spare bits of toilet paper and paper towels, liquids and solids of undetermined origin (or rather, origins you don't want to think about), and a toilet bowl that was possibly installed discoloured, clogged and smelling. It's full of used syringes, sleeping hobos, dead hobos. The handles on the faucets and bowls may be missing. In this case, it is probably better to just go in the woods behind it.

Part of the reason this trope exists is a form of the GIFT. While clearly not on the internet; the idea that anonymity and lack of consequences/responsibility leads to complete asshattery is still demonstrated. People naturally expect privacy in the restroom, and public toilets are not cleaned by them, so they feel less guilty for trashing them, scrawling insults on the wall, or insulting their peers.

This trope of course comes from Real Life, as anyone who's ever had to go at a rest stop, a park bathroom etc. can attest. Even an ill-maintained flush toilet is extremely disgusting, but pretty much any toilet without flush technologies is going to be worse (even Porta-Potties tend to be a borderline case). Outhouses and latrines were once a familiar and disgusting part of everyone's life, and while they are now rare in the industrialized world, they're still necessary in a situations like wilderness camping or a Third World village; therefore, the outhouse isn't something that will ever become so obsolete that people entirely forget such a nauseating (but necessary!) phenomenon.

Can be played for laughs or just plain Nausea Fuel. Contrast with Wondrous Ladies' Room.

No real life examples, please; we'd be here all day. Also, All The Tropes does not care to squick its readers.

Examples of Disgusting Public Toilet include:

Advertising

There's this commercial where a drag queen has to make a stop at a truck stop toilet, which is naturally horrible - then she brings out the product advertised and turns it all sparkling.

"How was the restroom?"
"Fit for a queen."

There's a Lysol ad that starts out with a woman taking her daughter into such a restroom, making the point that your own toilet might be just as full of germs. Mocked in one of Current's Target Women segments:

Sarah Haskins: Why are you taking your kid to the bathroom in Grand Central Station in 1972?!?

Comic Books

In an early episode of the Marvel series Excalibur, Kitty Pryde needs to answer a call of nature while being carried by Meggan across the Atlantic. They spot a freighter and land on it so she can go to the restroom, but the place is disgustingly filthy.
In Like a Velvet Glove Cast In Iron there is one of these located in a porno theatre. Inside a special cubicle is a Hindu wise-man who starts our hero (Possibly Anti-Hero) on his quest to find his wife. Uh... and some other stuff.

Fan Works

In the The Lord of the Rings Fanfic Don't Panic, the Prancing Pony restroom is one of these. Obligatory comparison to the bathroom from Trainspotting ensues.

Film

"The Worst Toilet in Scotland" in Trainspotting. Including cringeworthy scene where the hero dives into the toilet bowl.
'The worst toilet in Scotland' was also referenced in Gorsky and Butch: In a pastiche of The Matrix, the whole team escaped through the pipe, with Morphinius staying behind to flush them. It resulted in The Can Kicked Him when agent Butch caught up with him.
The Port Authority bus terminal bathroom is like this in Nick and Norah's Infinite Playlist.
In Desperado, the entrance to the secret room is concealed within a truly disgusting bathroom stall.
The setting for most of the first Saw movie.
Subverted in The Warriors. The bathroom in which the Warriors face the Punks is a bit grungy, but it's nowhere near as bad as one would expect from a public mens' room in a New York City subway station.
The public bathroom in Halloween H 20 is a good example of this trope. It's dark and grimy, the faucets are leaky, the floor is covered in litter and there is no toilet paper in the stalls. One wonders why the mother didn't just tell her daughter to pee in the bushes. At least then, it would be much more hygienic!

Literature

Dave Barry described places like this as either "not having been cleaned since Rome fell" or "containing the skeletons of Health Inspectors who died trying to examine it". A column about summer camp referred to it having the sort of latrine where you wonder how it could get so disgusting when nobody ever has the courage to use it.
Referenced in the first Harry Potter - apparently, mountain trolls smell like a cross between old socks and "the kind of public toilet no-one seems to clean."
Jeff Foxworthy: "If you wonder how service stations keep their restrooms so clean, you just might be a redneck."

Live-Action TV

Mike Rowe in Dirty Jobs has seen some of these.
Subverted in Monk. Monk expects the men's room at the theater to be like this, but instead it's incredibly clean and even has an attendant offering a variety of scented soaps.
The MTV show Homewrecker, which modified the bedrooms of pranksters into unlivable disaster rooms (think Trading Spaces or Extreme Makeover: Home Edition turned on their heads), turned one room into one of these.

Music

"Weird Al" Yankovic's song "One More Minute" details all of the disgusting, painful, and generally unpleasant things the protagonist would rather do than spend one more minute with the girl who has just dumped him. One of these things is cleaning all the bathrooms in Grand Central Station with his tongue.
The Frantics' song "Gas Station Washroom" explores this trope as though it were the centerpiece of a horror movie.

Professional Wrestling

The restroom with the overflowing trough urinals in No Holds Barred at the "Battle of the Tough Guys" venue.

Video Games

Silent Hill 2 opens in one of these. James eventually plunges his hand into one of these to get a key. Ugh...
Silent Hill 3 also features equally disgusting toilets, though unlike James, Heather outright refuses to stick her hand in one if you have Silent Hill 2 save data on the same memory card.
Fahrenheit (2005 video game) starts with a grisly murder in the Disgusting Toilet of a Greasy Spoon.
The restrooms in the adventure game Dark Fall: The Journal are fairly gross, and they've gotten much, much worse in the latest sequal, Dark Fall: Lost Souls. Averted in Dark Fall II: Light's Out, as the tourist restrooms on Fetch Rock 2004 aren't filthy, they just need their trash bins emptied.
This can be a randomly-rolled fear of a Sim who has high cleanliness or low outgoing scores.
- Actually, they fear using a public toilet at all, even if it's clean.
In Hector: Badge of Carnage Hector starts the game by having to fish out something out of a toilet in the prison cell of a police station which while not 'public' fits the trope completely. After many other disgusting bathroom jokes and puzzles, episode 3 has you interacting with the portable public toilet at an outdoor festival.
The original Leisure Suit Larry has a disgusting toilet in Lefty's bar which floods and drowns the main character if flushed.

Web Comics

San Antonio Rock City "Autobiography II"
In Daisy Owl, the Rest Stop bathroom described by Mr. Owl is a humorously extreme example.
This installment of Better Days.
Subverted in this El Goonish Shive. Someone really takes pride in keeping that gas station bathroom clean.
In this I'm My Own Mascot comic, this leads to the destruction of the Earth.
An old sub-comic hosted on Bob and George, Jailhouse Blues, featured Nasty Toilet Man, the multiple failed attempts at defeating became a running gag of sorts. He was finally beaten with More Ammunition Than God and a microwave.
In this Death and The Maiden comic, the protagonists try to loose one of Deah's 'accidental' corpses in a public bathroom stall, getting second thoughts when seeing the stall. Nobody, they reason, would sit there - not even to die.

Web Original

The website Retail Hell Underground has an entire section dedicated to this. Let's just say...people do some really disturbingly gross things in public bathrooms, and sometimes even worse, when people don't even make it to the toilet, or when they mistake the fitting rooms for a Bathroom Stall.
- The book Retail Hell by Freeman Hall, one of the founders of Retail Hell Underground, describes a story in which he walks into the bathroom and finds that someone had taken a massive dump in the urinal, and nobody could use the men's room for the rest of the day. He also describes a very disturbing incident involving a fitting room disaster...Let's not go there. Too Much Information. Really, let's NOT.
Cracked.com's topic page on public restrooms has a normal, decent restroom gradually becomes one.
In East Park 3. the toilet bathroom has Xenomorph eggs in it.
There's an SCP called The Worst Place/Thing In The World which is located inside a porta-potty. It's driven all who have seen it, even over a video feed, insane. So do most SCPs really, but this one does a really good job of it.

Western Animation

On Foster's Home for Imaginary Friends, Bloo has to stop at a truck stop to go to the bathroom, and he wears plungers on his feet "because public bathrooms are so grody" and he wants to keep from stepping in the germs.
In Animaniacs, the episode "Potty Emergency", Wakko is in a desperate search to find a bathroom and arrives at a gas station. When he turns on the light, the entire wall seems to recede: It's covered ceiling to floor in cockroaches, and the rest of the horrors within are mercifully implied by Wakko's reaction to it rather than shown to us.
- In the Animaniacs movie, King Salazar's torture routine involves a trip though the same restroom. The attendant's previous warning of "I haven't cleaned it in a year" is changed to three years. Played for Laughs, obviously.
In a Tiny Toons Direct to Video movie How I Spent My Summer Vacation, we don't see a bathroom, but we do see Hampton's family suit up in hazmat type suits so they can clean the public bathrooms before using it.