These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Religious fundamentalists (sometimes extended to theists in general). Atheism isn't particularly well-liked either nowadays, as the site would often be filled with Hollywood Atheists who were just mentioning it to get attention. Mention your atheism now and you'll be flooded by "So brave" comments.
Any politician who's not Ron Paul, Bernie Sanders, or Elizabeth Warren. Especially if they're Republican.
Gawker, which is hated for its political correctness, and often accused of inflammatory tabloid-style clickbait
Tumblr, the Sitcom Arch-Nemesis to Reddit and considered its Evil Twin - its bigger focus on images, the average user being female (and sometimes non-white), and, of course, everything that Reddit is not when it comes to social justice. Especially so on the r/thathappened and (obviously) the r/tumblrinaction subreddits, but, surprisingly, not the case for, uh... r/tumblr.
For r/shitredditsays, Straight Able-bodied White Cisgengered Males (SAWCASMs). For Straight Able-bodied White Cisgengered Males (SAWCASMs), r/shitredditsays.
r/cringe (and by extension, r/cringepics) loves to make fun of bronies.
Ironically, STEM majors themselves, thanks to the stereotypical attitude some Redditors have toward them (read: if it's not a hard STEM, it's for idiots and doesn't get money). Especially hated in the Fempire and Circlebroke. Expect a flame war to break out between liberal arts majors and science majors whenever it pops up.
Brain Bleach: Needed for r/spacedicks, a Shock Site in the vein of Goatse/Pain Olympics (with a dose of randumb humor.) Mentions of it on other subreddits tend to garner "SWEET JESUS WHY DID I CLICK" responses and requests for Brain Bleach.
There's a subreddit called r/Eyebleach where users post cute and sexual things. "After a long day of seeing what internet anonymity can do to people, you're bound to need some eyebleach."
r/shitredditsays: Straw Feminists with Hair Trigger Tempers or a useful antidote to the rampant misogyny on Reddit? Either way, whenever a post gets featured on SRS, expect a flame war to break out between regular Reddit and SRS in the post itself.
r/mensrights and r/atheism are both very popular but also considered two of the worst subreddits to the point where there are multiple blogs and videos dedicated to bashing them, and the mere mention of them on Reddit (or offsite) will result in a Flame War.
A number of subreddits have split due to in-fighting. Perhaps the most infamous being the migration from r/marijuana to r/trees due to a controversial moderator.
Broken Pedestal: The user u/Unidan, who had built up a reputation as a knowledgeable biologist and becoming one of the most well-known and liked Redditors, was revealed to had been using alternative accounts to upvote all his submissions after he and another user engaged in an argument over the difference between crows and jackdaws.
Browser Narcotic: We're not joking when we say Reddit is more addictive than TV Tropes!
Berserk Button: Comcast, if there is any "worst things ever" it's always mentioned.
<holds up spork>
Discredited Meme: Other communities tend to view Reddit using a meme as causing this.
With 4chan, although it is a bit more one-sided. 4channers are shown to despise Reddit, whereas Reddit seems to admire some of the more intelligent/witty posts that manage to come out of 4chan. (4chan thinks that this is stealing.)
And with Gawker Media. Redditors have always hated Gawker for its alleged pandering to the Lowest Common Denominator, and it only got worse after Violentacrez's doxxing/departure. A few subreddits even banned links to Gawker's sites
Also with Something Awful. Something Awful hates the site for being a haven of what they consider everything wrong with the internet, partially due to some child porn subreddits that have since been purged.
Some SA goons started ShitRedditSays, a documentation and mockery of all things considered wrong with Reddit's very politically incorrect vibe. Both goons and Tumblrites use SRS, and both will be happy to tear apart every vaguely creepy or hateful comment that pops up in the subreddit.
In response, Redditors started r/TumblrInAction which makes fun of otherkin and social justice warriors on tumblr and in general.
"Funny Aneurysm" Moment: A video of a guy complaining about constantly being rejected was posted to r/cringe just 4 days before said guy later shot 6 people dead. Most of the Redditors in the thread mocked the guy and thought he was too much of a childish idiot to actually harm anyone.
Humor Mode: r/circlejerk and any variant of the "circlejerk". Amazingly, clueless newbies will fail to see that it's a complete joke.
The site has generally gotten a lot of flak since its sudden rise in popularity when Digg changed its layout.
The popular default subreddits are particularly criticized. The common advice is to unsubscribe from those and subscribe to smaller subreddits instead.
Many state that subreddits start to lose quality once they get over 10,000 subscribers.
Know-Nothing Know-It-All: What a certain Imageboard would like to believe its Redditors are. With the extremely casual and accepting fanbase, accounts designed around karma, and discussions sorted by date as well as by likability, Reddit is the antithesis of its competition, which "ironically" uses Rage Comic edits as mockery. The unfortunate result of the karma system is that downvoted comments, even if they have merit, are quickly shoved aside. It's really up to personal preference.
Narm: An insightful, informative posting can seem jarring when coming from a silly username.
Or it may just be the content of the quote. One now-infamous example reads as the following: "In this moment, I am euphoric. Not because of any phony god’s blessing. But because, I am enlightened by my intelligence."
Outside of Reddit, the site's becoming known as a haven for pedophiles and misogynists, to say nothing of its reputation with 4chan and Something Awful as an unfunny ripoff of 4chan memes, shitty internet humor, the worst of social awkwardness, and an echo chamber for militant atheists and libertarians. And ruining fedoras. Even though the Subreddits responsible for Reddit's reputation (r/Creepshots, r/Jailbait, among other things) are now gone, were heavily derided and avoided by the userbase before their deletion, the defense of the subreddits existing as a form of 'free speech' only sealed in Reddit's reputation.
The subs that are havens for bigots (such as r/TheRedPill, r/Atheism, and r/MensRights) are also laughing-stocks outside of their own sphere of the site.
Reddit once actually tried to find the Boston bombers, got the wrong person (and a dead one, to boot), and harassed their family. It's brought up a lot when people try to organize witch hunts or play internet vigilante.
Even as important as having a high karma score is, some users try to get as much negative karma as possible by posting offensive comments.
SRS has this to thanks for its notoriety, which the SRS mods even acknowledge. People from other subreddits insulted or railed against SRS, leading to more people checking out the subreddit just to see if was really so bad and finding themselves agreeing more with the Fempire than with SRS's detractors.
Political Correctness Gone Mad: What everyone thinks about r/shitredditsays, except r/shitredditsays themselves of course. Not surprising, as it's pretty militant in tone, quick to ban, and happily admits to being a "circlequeef".
Ron the Death Eater: SRS loves to do this to Reddit as a whole, painting all of its (male) userbase as racist, misogynistic pedophiles. The rest of Reddit, in turn, treat all of SRS as evil, humorless, man-hating harpies, which SRS gleefully mocks.
Rule-Abiding Rebel: The "So brave" meme was created to make fun of users that claim to have controversial political and social opinions, but largely conform to acceptable opinions on reddit. "So edgy" is a similar catchphrase in SRS comment threads, with many of the same connotations.
r/shitredditsays, Often accused of Political Correctness Gone Mad due to its hair-trigger nature, they in turn consider the rest of Reddit this due to how easy finding bigoted comments can be in certain subs.
r/jailbait, r/creepshots, and similar/related subreddits. It's a long story. The short version: Reddit's mods were reluctant to remove even subreddits distributing child porn and photos taken without consent because it was "against free speech"; it took media attention and a long campaign by Something Awful and affiliated sites for anything to be done about them.
Gawker Media. Already unpopular with reddit beforehand, Gawker published an expose on violentacrez (the creator of r/jailbait and various other creepy subreddits) that lead to him being fired from his offline job; a number of subreddits subsequently banned links to Gawker.
"Power users" with loads of comments and karma inevitably attract a hatedom, because internet points are Serious Business.
"Novelty accounts" (users who operate on a single gimmick, such as AWildSketchAppeared making a sketch of a comment or ActuallyTwoLlamas posting an image of two llamas instead of a relevant image), when the joke wears thin.
Throwaway accounts are also controversial.
The Cringe subs are starting to fall into this based on accusations that they've become more about bullying people that do/enjoy/believe things the poster doesn't like than actual cringe.
Then you have the people who complain about the people who complain about reposts.
People who complain about people putting punchlines of pictures in the title whether the punchline would actually make sense without the context of the picture have been called this as well.
They complain EVEN if the picture's questioned punchline isn't even the punchline to begin with.
People who complain about memes, or people who complain about using memes "incorrectly."
People who complain about image posts.
Many posters on r/malefashionadvice will simply put down someone asking for an opinion on some even slightly out-there clothing item. There's a reason the sub is derided on the rest of Reddit for promoting a "template" look.
/r/circlebroke and r/negareddit, having a tendency to dislike anything deemed popular on the rest of Reddit. /r/subredditdrama also can dip into this, depending on what group of users are perusing it at the time.
SRS really, really hates any politically incorrect jokes, especially highly-upvoted ones. Jokes about having sex with inanimate objects have been featured on the subreddit.
Complaining about mystery downvotes on a neutral comment.
For some odd reason, any comment or edit pointing out the neutrality of a comment will get downvoted even harder.