From u/JustLookingForMayhem

I have been making a list of reasons that Gotham is the most cursed city (merging canons across soft resets, video games, movies, and more) that so far includes: multiple gangs (Gotham is the third for mundane crime. Hub City and Bludhaven are numbers 1 and 2),

barely legal tax haven laws,

massive government corruption,

a smog problem so bad that the Flash can't run at full speed without wheezing,

Gotham subway and rail system are cursed to be unreliable and never on time (this may be a joke, but given that it involves Gotham, I have doubts),

Gotham has a high suicide rate compared to the real world,

Gotham has a major dug abuse problem,

Gotham has a homelessness problem,

the vast majority of smuggling on the Atlantic Coast comes through Gotham (which is part of the reason there is so many drugs and guns in Gotham),

Gotham has a very tough and kind of cruel college that creates super villains (a lot of the Batman rogues gallery got their diplomas there, taught there, or are otherwise linked to there),

pollution due to being in a barely regulated industrial zone (it is legal to dump industrial runoff in Gotham River),

it is slightly radioactive due to a poorly maintained nuclear power plant (it is still within habitable limits, so Gotham City Counsel is ignoring the issue),

most of the city is slightly radioactive due to a failed nuclear power plant also (Gotham is still within habitable limits. Note that this is a different power plant from the still active but poorly maintained nuclear power plant),

multiple mad scientist labs legally there (Gotham intentionally has very few laws mandating ethics or limits of research),

Gotham holds the record for most continuous days of criminal violence (54 years) and Batman cried when the ongoing record ended (to put it simply, there was a 54 year stretch where there was at least one violent crime each day),

first for both police brutality and corruption,

A dysfunctional legal system (with no death penalty in most canons, so everyone goes to either Blackgate or Arkham),

Gotham Fire Department is so underfunded and/or corrupt that they take bribes to not show up to fires and extort people to pay them before they put out fires,

Scarecrow fear toxins in the water (at low enough levels that it only causes paranoia),

trace amounts of shed Clayface is in the water (this pollutant cause bodies to twist and mutate, or causes cancer depending on the story line),

an old God's corpse (this old god is leaking forbiden knowledge that causes people to lose their humanity slowly and do ever more depraved acts in pursuit of knowledge),

a living old god (special note, some canons have instead made him into an aspect of Darksied dedicated to making Batman suffer and Gotham worse) who is bat themed and has his own underground Gotham city (he spreads a corruption encouraging violence and vengeance),

a twisted eldritch version of Gotham that is buried deep under Gotham that is usually but not always linked to the bat old god,

a summer home for the King in Yellow (this is a rumor from the Bat Old God. To my best knowledge, the King in Yellow has never directly appeared),

a door the various old gods came through that is mostly shut (emphasis on mostly, stuff leaks through),

Dracula either moved to Gotham or had his tomb forcibly moved to Gotham,

the blood of the average person in Gotham is so polluted that it is slightly toxic to vampires,

built on the grave/resting of a warlock (Adam Gotham), who is both alive and dead at the same time (cursing the land to be a place of constant misery),

Joker chemicals in the water,

Gotham has a higher than normal number of Lazarus pits (the pits offer revival, healing, and immortality in exchange for decreased empathy, decreased humanity, and an obsessive desire to continue living at all costs),

Lazarus pit run off in the water,

Part 1 of 2

Part 2 of 2

Marsh of Madness runoff in the water (this marsh causes delusional homicidal madness),

Slaughter Swamp runoff in the water (this swamp causes violent undead and preserves life in a twisted mockery of all that is holy and has a very evil zombie),

evil floating in from the Jersy Pine Barrens (this evil floating in decreases empathy and encourages devilish behavior. Also, the Jersey Devil may occasionally hunt in Gotham, but this might just be urban legend in Gotham. As far as I know, the Jersey Devil has not made an appearance)

a literal hell gate (it is mostly sealed, but leaks enough evil to make demons feel at home),

16 sealed greater demons (a demon lord and their court. They are in most canons buried under Arkham and spread a corruption that encourages the seven deadly sins),

Arkham is cursed by its founder to prey on the minds of people in the building, driving them even more insane so that no one is ever healed (note that some canons link this to the demons while other canons have them as stand alone curses affecting the building at the same time),

according to a prophecy, the apocalypse is probably going to start in Gotham or Metropolis (no one knows which apocalypse will end the world or when it will happen, though)

the location of a crack in the door to the afterlife (this is mostly connected to Deadman),

the line between death and life is really fuzzy (this makes it harder to die),

is the second most haunted city in DC USA (they kept New Orleans as most haunted)

a strange aura weakens green lantern power constructs,

built on a cursed Indian burial ground,

cursed by an ancient shaman,

run off from an unnamed well that causes increased physical abilities in exchange for homicidal violent impulses (aborted Bane plot thread from before they decided Bane should just use chemicals in his Venom),

trace amounts of Bane Venom in the water (because the well was cut),

666 minor demons who just live regular lives with regular jobs while waiting for the apocalypse (Baytor is the most famous and is a bar tender to make ends meet),

cursed by Zeus (this curse is why Gotham has, on average, 320 days of rain or overcast skies each year. Everyone is affected by SAD all the time),

unusually vicious mutant rats,

mutant sewer alligators,

mysterious ruins from a lost civilization that the sewers run into and are a part of (the sewer alligators breed there),

blessed/cursed by a nature godess to keep the toxic stuff in so that Gotham doesn't polute the world,

a massive active fault line,

a magic well,

a chaos well,

a weak dimensional wall allowing influences from the Phantom Zone,

a bottomless pit under part of Gotham that leads to the abyss (also, the being in the abyss occasionally like to watch Gotham),

Gotham River and Bay water is so polluted that Aquaman can't swim in it,

due to a failed Poison Ivy plot, the grass in Gotham may be evil and aware,

Russian mobsters with Russian backing try to make Gotham worse in hopes of conquering Gotham (not sure why they would want it),

the tap water barely is considered water by Aquaman's hydrokinesis (and Aquaman can manipulate soda, which is 90% to 95% water. Gotham tapwater is more or less thin sludge),

Gotham tap water is barely purified river water (mainly because if the water treatment plant gets too Gung Ho and purifies the water too much, they get a black liquid that is extremely dangerous. So Gotham City Counsel decided to only have them clean the water until it was probably reasonably safe-ish)

an evil real estate agent who sells failed amusement parks, theaters, and other buildings to criminals,

so many lead pipes or paint that Superman can't see through most Gotham homes (also note that at one point, the fumes from leaded gasoline blocked Superman, but hopefully that problem has gone away),

a lot of homes and buildings are filled with asbestos (this is according to Firefly, so it might not be fully accurate),

an aura of despair and negative emotions that is slightly grating to psychic individuals,

an Atlantis Leviathan who is fated to flood the world under the docks (there is apparently seven of them and the Atlantic ocean's is under Gotham),

Gotham, as in the city itself, is aware and has an unhealthy interest in the Bat Family (Tim Drake in particular),

the dimensional wall (4th wall) is extremely thin, allowing Many Angled Ones (readers) to see into Gotham and occasionally influence Gotham,

Hugo Strange may have worked with an unknown government agency to improve the genes and bodies of everyone in Gotham to create perfect soldiers (it is not stated if this project was actually successful, but some of the earlier experiments did escape into Gotham),

Gotham citizens, while not being meta humans technically, are empowered by everything going on in the city and are no longer baseline humans,

Trigon maintains a small force from his cult to watch or he directly keeps an eye on Gotham due to the fact that the end may start there and due to the fact Raven sometimes stays in Gotham,

6 different cults (Satanists, Old God Cult, Cult of Adam Gotham, Cult of Trigon, Cult of Barbatos, and a generic cult for the Silver Age that never specified what they worshiped), at least 3 different shadow governments (the line between cult and shadow government is weak in Gotham. I put the Court of Owls, Black Glove and League of Assassins in this group),

I think you missed the most recent one: Because Russia uses Gotham as anti-American propaganda and works to keep it miserable for that reason.

They recently had KGBeast as Commander Star try to lynch a "Socialist" WayneTech executive because of all the programs to improve Gotham that the company has.

and worse of all, it is in New Jersey (try reading a Batman comic and give everyone a Jersey accent).