Nodame's apartment in Nodame Cantabile is like this whenever Chiaki isn't around to clean it. How her piano stays in a playable state is anyone's guess.
Lain's house in Serial Experiments Lain gains a worrying amount of mess and a nasty brown fog near the end of the series, when Lain's family turn out to be adoptive and goes away, leaving her alone there.
Howl's house in Howl's Moving Castle. Strangely enough, Howl seems to prefer it that way—but Sophie cleans up after him nonetheless.
Sheska of Fullmetal Alchemist is not a slob, but her room is absolutely full of unsorted books. So much that's she introduced needing rescue from being buried under a pile of them that fell over.
Sato's apartment from Welcome to the NHK definitely counts. He at least tries to keep things marginally tidy during his 'oh god I'm a hikkikomori' moments, but for the most part, its a sty.
In the Zan Sayonara Zetsubou SenseiOVA we're introduced to KitsuChiri's older sister, Kitsu Tane, who is her complete opposite. It is explained that in their childhood, Tane chose to become The Pig Pen in order to save the life of their gold fish, which Chiri had decided to clean. Unfortunally for Tane, she had to maintain this behavior for so many years, it eventually got stuck (literally; trash seems to follow her) and now she can't even take properly care of herself... To end on a positive note, if she hadn't kept Chiri's obsessive compulsive tidiness in check with her Heroic Sacrifice, Chiri might've doomed humanity by the time the series started, considering what becomes of her when something is not perfectly perfect.
Great Teacher Onizuka Onizuka's apartment is not only tiny, but a wall-to-wall landfill. A can of ramen with a hole in it is the least embarrassing thing there.
Taiga's apartment in Toradora!, with a sickening stench emanating from the kitchen sink which was polluted so heavily that its contents were censored on screen. Naturally, she is complemented by a Neat Freak co-star named Ryuuji, whose first reaction to seeing said apartment is to beg her to be allowed to clean it. Since Taiga is a very Lonely Rich Kid living by herself and only returns to her apartment to sleep (her bedroom is the only room that's not covered with a carpet of trash) she just doesn't care enough about it or spend enough time there to hire anyone to clear it for her even though she clearly has the means to.
Naeka's house in Kamen no Maid Guy was so filthy that Kogarashi has to cart out living snakes and ravens.
At the start of Mahoromatic Suguru's house is practically a biohazard, until Mahoro comes to provide her services.
His (unwashed) underwear had mushrooms growing on them.
Never, ever attempt to find anything in Komui Lee's office.
Or Lavi and Bookman's old room.◊ Granted, it's only paper in the end, but I can't imagine it not also being trash since they are supposed to remember everything they've read. And just imagine the dust..
The student-run dorm in Moyashimon is a dump, especially Misato and Kawahama's room, which is just one big wall of mold spores from the perspective of main character Sawaki (who has the power to see microbes).
Shigure's house in the beginning of Fruits Basket, with both Yuki and Shigure unable to bring themselves to clean it up. Later on, Tohru makes a comparison about dealing with problems along the same lines of doing a mountainous amount of laundry. Reflecting back on things, it's quite likely that metaphor was a bit more literal for her.
Machi also has this problem.
Shigure's room isn't much better. Even once Tohru's cleaned up the rest of the house, it's still a junkyard of epic proportions.
Tenpou in Saiyuki Gaiden has an office/library that becomes like this frequently and would get worse if Kenren didn't clean it for him. Weirdly in their future incarnations this switches.
In Kochikame, Ryotsu's room is basically like this.
Erica Hartmann's room from Strike Witches. She also shares the room with another girl, Gertrude Barkhorn, who has it divided in half by a wooden barrier. Barkhorn refers to the barrier as her 'Maginot Line' and is horrified if even one piece of trash finds its way past. It's so messy that in one episode, she can't even find her underwear, so she ends up stealing a pair from one of the other girls taking a bath at the time. Hilarity Ensues as they try to figure out who stole the underwear.
Onegai My Melody had a guy who was a total slob, his house is filled with trash bags and he sleeps on and under them.
Gaea's place in Noob before she turns out to have a roomate.
Sith Academy had this as a running joke; the Dark Side always leaves a visible sign of corruption on its users, and for Maul it was that any area he lived in for more than a few hours at a time would inevitably become a pig-sty. There were mentions of civilizations rising out of the trash he left lying around, as well as at least two (maybe three) on-screen encounters with civilizations that emerged from his fridge.
In A Cure for Love L resorts to just throwing off the huge stacks of paperwork, trash, and finger puppets from the hotel's (taskforce HQ's) coffee table in order to find his missing lollipop.
"The Great Garbage Avalanche of 2505" in Idiocracy. They had mountains of garbage at least as high as some buildings, streets were littered, etc.
The entirety of Earth in WALL•E. So much, that Wall-E was making skyscrapers from the blocks of trash he compacted.
The airport in The Fifth Element has a mountain ridge of trash running through it due to the janitorial staff being on strike.
In Worlds Greatest Dad, the neighbor is revealed to be a compulsive hoarder, making her as much of a recluse as Robin Williams.
One of the Red Dwarf novels has mankind turn Earth into the Solar System's trash heap (leading to an Earth All Along when Lister recognized Mount Rushmore). At least until it 'escapes' when a methane vent ignites and the Earth farts out of orbit.
Lister generally managed to create a smaller but no less deadly version of this in his living quarters.
"No way these are my boxers. These bend!"
In The Long Dark Tea-Time of the Soul, Dirk Gently is having a standoff with his cleaning lady over who will open the fridge first; it hasn't been opened in several months. The rest of his flat is in a similar state. Eventually, Dirk just buys a new fridge and has the old one carted off, where it spawns a new demon/god which conveniently eats the escaping 'villains'.
In So Long, and Thanks for All the Fish by the same author, Arthur Dent's room is in a similar state, as he jokes "Bung a fork of lightning through this lot and you'd start the evolution of life all over again."
Roadside Picnic by the Strugatsky Brothers demonstrates what happens when Sufficiently Advanced Aliens have this trait. Basically, all the mysteriously advanced (or just extremely weird) materials and objects found on Earth after some sort of unexplained incident are... the trash & fast food wrappings left over from some not-particularly-careful extraterrestrial tourists (For those not in the know, this book was the basis for Stalker.)
The Wyler/Garin household in Stephen King's The Regulators. Autistic 8-year-old Seth and evil possessing entity Tak doesn't care what the place is like, and his aunt/guardian Audrey, the only surviving adult in the household, has much bigger problems occupying her time and energy.
In "The Musgrave Ritual", Watson grumbles about Sherlock Holmes' tendency to fill their shared flat with stacked papers and oddly-placed personal items, not to mention shooting decorative holes in the wall. Subverted in that Holmes actually does have "a system" — at least, he can swiftly lay hands on any document he needs — and his accumulated bric-a-brac at least isn't the sort of stuff that decomposes.
In the Nightside series, Suzie Shooter's place is like this. John speculates that the only reason she doesn't have rats is because she eats them.
Dave Barry once wrote a column called "Subhumanise Your Living Room", which is essentially a tribute to this kind of decoration. He describes that his college dorm contained little furniture except for an orange blinking light and a cardboard submarine, and the walls were covered in caked crepe paper.
Subversion: Lovecraft'sThe Shadow Over Innsmouth - there is a general degradation of the town and houses crumble in their own dirt after decades of neglect, but the reason behind this is the lack of motivation for the monstrous inhabitants to make the smallest repair, since they are mutating into deep-water creatures and they will leave the town anyway.
In one episode of Friends, Ross goes out with a beautiful scientist who happens to live in an absolute mess of an apartment. Joey doesn't seem to care much about spilling stuff or making a mess either, but since he lives across the hall from obsessive neat-freak Monica she occasionally makes clean-house-calls. She even showed up at the above mentioned scientists' apartment begging to let her clean it. That said, she also has a massive collection of trash in her own apartment, hidden behind the mystery door. Chandler is shocked when he finally gets it open.
The television Ur Example would be Oscar Madison from The Odd Couple, which was also a play and a film. A TV Land Commercial pokes fun at this by using a fake-cross section of the bed, with an increasingly disgusting and improbable item down the hundreds of layers pointed out.
The book shop in Black Books became this way after Manny had run off. Even while he was there, it got so bad that he had to eat "scrambled eggs...with a comb...from a shoe!" A cleaner put on a white glove, and it turned black when he ran it along the air. It had also begun to play habitat to "something with fur and a beak". I like to think it was a chicken riding pig riding a bear. And it got much, much worse after he left. For example, "Turn left, at the dead badger."
The family's house in Malcolm in the Middle. One episode revolves around them cleaning out a closet and finding property and mail belonging to the people who owned the house before the people they bought the house from, and they ultimately discover that the "closet" is actually a spare bathroom, but it was so full of junk that they never knew it. Another episode features Lois taking medication that prevents her and Hal from having sex and they channel all their pent-up energy into improving the house. At the end, Hal is convinced they have tripled the property value, but now Lois is off the meds and it soon goes back to the way it was.
The main point of How Clean Is Your House? is seeing Kim and Aggie scream and squirm at the unbelievably messy houses they come across.
When Burke sees Cristina's apartment for the first time on Grey's Anatomy, he is a little shocked that Cristina is messy. Cristina monologues about the mess and states that she once hired a maid... who ran away crying.
Hoarders, a Reality TV series about people with compulsive hoarding. Things get even more perilous when people refuse to throw out food ("The milk's still good 'cause the carton's not puffy! It's just the outer layer of the lettuce that's gone bad! Oh... I think that was a pumpkin..."), pet hair ("I know it's stupid but it protects my dog... somehow"), or guns ("I've heard him threaten to kill her more then once"). Strangely, only two groups of subjects were Crazy Cat Ladies, and the more serious one had about 50 animals (about half of them were still alive, and about half of those had to be put to sleep due to aliments caused by the horrible conditions).
The first time we see Leslie's apartment she admits to being something of a hoarder.
April and Andy's house is worse; they don't seem to understand the concept of cleaning.
In the House episode "The Dig", the team treat a man who they believe to be a hoarder after seeing his house, whose illness is a result of this. When they search his house more thoroughly, they find his wife, even more sick that her husband and the actual hoarder.
On Glee, it's implied that Santana keeps her car this way, to the point that Brittany suggests she be on Hoarders.
In one episode of Babylon 5 Londo has a slight bug problem. It starts when he finds an insect in his quarters, a big one, and ends up impaling it with his ceremonial dueling sword:
Londo: *To insect on end of sword* HA HA! There, you see! This will teach you to... Trifle with a Centauri, you triple-damned... *Examines it closer* You know that... You know that you are smaller than I thought you were? [beat] Londo: ...You are smaller. There are more of you!... THERE ARE MORE OF YOU!
**Later in the episode**
Londo: If you see something this big with eight legs coming your way, let me know. I have to kill it before it develops language skills.
Few of the reality show examples are quite as bad as Mr. Trebus, unlikely star of Environmental Health Docu SoapA Life Of Grime, whose compulsive hoarding of rubbish had weakened the structure of his house.
In Cases of the 1st Department, major Vaclav Plisek's desk at work is always disorganized and messy. Major Tomas Kozak often tries to convince him to clean it, especially if Plisek can't find important papers or his glasses. In episode "A Policeman to Gun Down", they have to look though a suspect's garbage. Kozak comes later and jokes that he's pleased that Plisek decided to clean up. Surprisingly, Plisek's home is clean and cozy, even though he's an old bachelor.
In the video to Donna Summer's "She Works Hard For The Money", an overworked waitress and mother of two returns home after another long day. The camera pans around her living room, which is an atrocious mess she's far too exhausted to bring under control.
Older Than Feudalism: In Classical Mythology, Hercules had to clean the stables of King Augias, which hadn't been cleaned in over twenty years. Poor cows! He rerouted a river to accomplish it, flushing the stable like a giant toilet. And then the Labor was invalided because he didn't use his own muscle to clean the stables, instead using the river. Herc couldn't catch a break.
This trope describes Jeremy's bedroom on any given day in Zits.
A morbid example from Warhammer 40,000; ChaosSpace Marines of the WorldEaters Legion wear power armor known for its distinctive crimson paint scheme. At least, it was assumed to be a paint scheme. As learned by a slave forced to clean a suit, their armor actually bears its original blue and white paint; the red is actually layer upon layer of blood, caked on from countless victims over the millennia. Seems the author got the facts wrong. Old, caked blood isn't crimson, it's black, or, if it's somewhat fresh and in a thin enough layer, a kind of rusty red. In fact, dried bloodstains are often almost impossible to distinguish from the rust stains without proper chemicals. It's kinda understandable, given that the main oxygen-bearing agent in a human blood is, well, rust. They spend most of their lives in a hell-dimension where the laws of physics are the playthings of crazy gods. The less said about Nurgle followers and their (lack of) hygiene, the better...
There is a whole sci-fi parody role-playing game whose PREMISE is that you are eking out your life from a whole PLANET full of trash that you have been exiled to. The very punk / crazy-over-the-top HOL even has it right in the name: Human-Occupied Landfill.
The Dust Men from inFAMOUS embrace this trope, as they built their base from pieces of steel plates and garbage over a park. They also construct some of their weapons for garbage as well. From annoying little spider drones to HUGE trash robots that are controlled by psychic hobos.
A Kingdom of Loathing quest centres on a bunch of trash littering the Nearby Plains. The problems can be traced back to a bunch of giants rooming together in a floating castle, and the fact that the one who's supposed to take out the trash is the one known for putting things off (such that your character only knows him as the Procrastination Giant). You solve the quest by spinning the chore wheel, making it another giant's job. (Before a 2013 update, the castle would suffer other problems once the Procrastination Giant was put onto a different chore.)
Persona 2: Maya Amano's apartment is a complete pigsty. Upon visiting it in Eternal Punishment, policeman Katsuya immediately assumes there's been a break-in.
Persona 3: In a similar case to the above, when Mitsuru notices Junpei's door open, she calls the police assuming it was a break-in. However, Junpei states that his room is always like that, embarrassing Mitsuru and Junpei.
Marisa of Touhou is a notorious thief that grabs anything that interests her. However, she lives in a small cottage, and it is filled with everything she hasn't bothered to sort or throw away (which considering her short attention span is a lot). At one point in Curiosities of Lotus Asia, Rinnosuke even manages to find the legendary Kusanagi-no-Tsurugi in one of Marisa's junk piles!
Seeing how Deponia is a Landfill Beyond the Stars, it's inevitable that pretty much everyone who lives there follows the trope. Rufus in particular is a subscriber, mostly because his hygiene is terrible even by Deponian standards.
Nina, Charles and Oliver's appartment in Rose Guns Days is such a mess Rapunzel first wondered how they could even manage to live there. The first thing she does is to quickly teach them basic notions of cleaning and ordering, as the three grew up in the streets and were used to living in these conditions.
The dorm room of the (male) main characters in College Roomies from Hell!!!. Spoofed when one of the characters is completely unaware of the mess, because the background is blank. Another character waves his hand, and parts blank background, which turns out to be a wall of fog emanating from all the garbage.
Ratliff from Eyebeam. The pile of mess in his room isarunningjoke throughout the comic. When Ratliff moves into his own house, Eyebeam comments that it is nice how the trash piles up to a lower level, only to be reminded of "the tides". Once, and only once, does Ratliff actually clean his room; Hilarity Ensues. A quick de-cleaning restores the natural order of things.
Sam: "Cool! I'll finally be able to see what color the carpet in my room is."
Fooker of General Protection Fault. His apartment is so filthy that it spawned a sentient slime mold named Fred, who becomes a main character.
Smosh episode "Magic Keyboard" starts out with this, courtesy of Ian. Upon finding said keyboard, Anthony happily deletes the whole trash pile at once.
Ian: My treasure! My sweet, sweet treasure! (tearfully) You'll pay for what you've done! (Anthony produces a dollar bill, then copies it several times)
Ed in Ed, Edd n Eddy. Also an example of The Pig Pen, his room is pretty much nearly uninhabitable for human life, including a bath tub filled with gravy.
Played literally in The Fairly OddParents when Timmy accidentally ends up trashing Mount Olympus while partying with them. The Greek Gods, being who they are, do the same to Timmy's house. In another episode, Timmy is ordered to clean up his room, which has become so bad that there are creatures living under his bed and grabbing anything they see as food, unidentifiable green molds, rats crawling all over, other stuff.
The Griffins' house in Family Guy becomes like this in "Breaking Out is Hard to Do" after Lois gets caught serially shoplifting.
This was shown to have happened in Earth's past in the Futurama episode "A Big Piece of Garbage". The city of New York had become so messy by the year 2000 that all of the landfills and New Jersey were full. The city sent all of its garbage onto a barge that traversed the globe for a number of years before acquiring a shuttle to send all of the garbage out into space. This comes back to bite humanity in the ass, as in 3000 the giant garbage ball has come back into our solar system and threatens to destroy the whole planet, leaving only a "smelly crater" where the Big Apple stood. Only Fry's skills at making more garbage in order to create another garbage ball of the same size saves the Earth.
In the Rocko's Modern Life episode "Trash-O-Madness", Rocko's house becomes so filthy that even his dirty underwear develops a form of intelligence and tries to crawl away. Rocko's house is also seen as absurdly messy in several episodes, although not every one; sometimes his house actually is acceptably clean.
The Trope Namer is the title of the 200th episode (which, notably, featured guest appearances by Steve Martin and U2), whose plot revolves around Homer's bid for sanitation commissioner of Springfield. He succeeds, but as usual his incompetence takes charge, leading him to fill the town with so much garbage that it must be uprooted and moved five miles away. It should be noted, however, that the show has also used this trope in several episodes prior to Number 200, such as:
"War of the Simpsons" has Bart and Lisa throw a house party and trash the house so bad that Grandpa starts crying, only to learn that Grandpa faked it so he could make the kids feel sorry for taking advantage of him.
"Homer Alone" has Homer looking after Maggie, while Bart and Lisa are at Patty and Selma's apartment and Marge is at a resort following an arrest for obstructing traffic.
"Marge in Chains" has Marge put in jail, and things get so bad that Homer is reduced to wearing Halloween costumes and when the kids try to clean up, they accidentally step on a man underneath the carpet who yells, "Hey, watch it!".
"$pringfield [or How I Learned to Stop Worrying and Love Legalized Gambling]" has Marge addicted to the slot machines at Burns' casino and the kitchen is a wreck, along with Homer's room when he's scared into believing the Boogeyman is coming after Lisa.
"Home Sweet Home-Diddly-Dum-Doodily" has Homer and Marge go to a spa and the Child Welfare officers find Grandpa asleep on the couch, Maggie drinking from a dog dish with the sign "I'm A Stupid Baby" on her back (which was meant for Lisa in a previous scene), and Santa's Little Helper having sex with another dog on the dining room table (not seen, but implied, according to the list of offenses one of the Child Welfare officers gave to Marge).
In "Bart After Dark" Homer and Bart make 'garbage angels'.
There are also little examples that aren't tied to the plot, like the goats eating out of the trash Bart didn't take out in "Itchy & Scratchy: The Movie", the moose going through Homer's uncovered garbage in "New Kid on the Block", the polar bear going through the garbage in "Homer the Heretic", and the fawn gnawing on the chair in the messy living room in "The Springfield Files".
Dan Vs.: Dan's apartment is always shown to be a pigsty. Dan notes that his home somehow gets messier when he's not even around.
Bill's house in King of the Hill is frequently very messy covered in food and beer cans, it's sometimes so bad it attracts pests, in one episode he was able to form a large pile of debris from the garbage in his house, and his bathroom is legendary among the other characters for being especially disgusting.
In Totally Spies! the girls seem to have become this after they start living together, causing Sam to become a Neat Freak to get them to clean the house. Ironically her room is also completely filled with trash.
Truth in Television: there are many reality shows (such as the above-named Hoarders) dedicated to professional cleaners visiting houses that have been absolutely overrun by filth. Also, you have probably met at least one person like this in your lifetime. If you haven't met someone like this, it just might be you.
In general, while the Romans were slight exceptions, virtually any city before the mid-1900's was this way, due to lack of public sanitation policy. These living conditions were a direct contributor to the various outbreaks of Plague (Especially the notorious Black Death), cholera, and other such diseases. It took centuries for people to brainstorm the idea of public sanitation and waste disposal, and longer still for it to be commonplace.
New York during the 1800s. There was so much filth and garbage it was incredibly difficult to live there without catching some sort of disease, and these awful conditions were part of what led to the New York City Draft Riots of 1863.
Cities in the 1800s and early 1900s were cesspools of disease. New York was one of the worst, along with London, but every crowded city would have this problem. This may have also facilitated the spread of the Spanish Flu pandemic.
The filth and overcrowded conditions in Paris in the second half of the eighteenth century were a contributing factor to the French revolutionnote Short version: The king had decreed Paris could not expand beyond its walls, for fear that the common people would take over the countryside and displace the nobility. Whoops.
Perhaps the scariest real-life version of this trope would be New York brothers Homer and Langley Collyer. Over 100 tons of garbage was found in their house, and they even built traps to keep people from stealing anything. Unfortunately for both of them, Langley was killed by the very traps they set, while Homer, who had gone blind some years earlier, was trapped by the rubbish and slowly starved to death.
"Big Edie" and "Little Edie" Bouvier Beale, depicted in the documentary film Grey Gardens, were another famous real-life example.
In 2007, the entire city of Naples, Italy was subjected to this. Factors blamed were incompetent local government, restrictive environmental laws, and infighting among organized crime. The city managed to clean up the most touristy areas somewhat, but that's just about it. Garbage collectors being controlled and/or threatened by The Mafia was mitigated by police crackdowns and offering armed protection to the collectors, but then there's that insignificant problem that the main city dump is already overflowing. And all the neighbours are vehemently against creating a new landfill on their territory.
This guy hoarded buckets of his own urine and feces.
On a smaller scale, many rapidly-urbanizing Third World cities don't have the infrastructure in place to handle all the garbage its citizens produce. In Cairo, for instance, garbage is sometimes stored on the roofs of houses.
The Cactus, a derelict Coast Guard tender moored in Puget Sound for many years, was loaded with "buckets of paint and epoxy; rusted steel plates, rubber hoses, PVC pipe, leaking pails of seam filler, old newspapers, mattresses, boxes of tiles and who knows what else" (The Seattle Times). It currently resides in a Seattle shipyard awaiting dismantling.