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.
Dude, Not Funny!: Every so often, some users like to spread a rumor on Twitter that some celebrity has died when they're still very much alive.
Or even worse, joking about city council budget cuts.
After the Newtown shooting, one troll flat out crossed the line by pretending to be the shooter on Twitter (@Blastinkids) and saying he enjoyed killing them. His account is currently suspended.
Ensemble Darkhorse: Pretty much everyone is following one or two Horoscopes (usually and obviously, their own).
Fan Dumb: Good Lord, there is a reason why so many people have grown to despise Justin Bieber and One Direction even if they were, at worst, neutral to them before. Beliebers and Directioners (among others, but they stand out the most) take it upon themselves daily to start trends about them for almost no reason, get in the way of actual world events, hijack anything tangently related, and get offended en masse by other users (or even Twitter admins) wanting them to just shut up already.
Notably, "CALA BOCA GALVAO", a complaint against an obnoxious sports announcer that somehow became a campaign for saving endangered birds.
Hate Dumb: There are people who refuse to get a Twitter account because of excuses like "I don't want people to know I'm on the toilet", etc. Never mind that it's up to the user to determine whether or not they want to make posts like that.
And then there are those who refuse to register because they think other people's streams are nothing but shallow self-indulgent posts, so not entirely fair.
Unrelatedly, there are (or seem to be) an endless supply of hate and troll accounts on Twitter. It seems Twitter is doing very little to prevent them from taking over, aside from a "Block And Report For Spam" button underneath every account's profile page.
Hype Backlash: As with any website with social networking elements, it gets quite a bit of this.
One such instance happened during the Suzuki AFC cup finals first leg where Malaysia won 3-0 against Indonesia and Indonesians accused Malaysians (which was the home team at that time) of pointing laser beam at its team's goalkeeper, despite there are proofs of Indonesians did it at first during group matches. It managed to top the trending for a few days, outdoing Justin Bieber.
Version 1.1 of its API. Among other things, it only allows clients to perform 15 API calls per 15 minutes (as opposed to the 150 or 360 calls per hour in 1.0), and all clients under 1.1 must conform to a series of "display requirements" that were not part of 1.0. This gives developers less freedom in how to design their clients, and users, particularly heavy users on mobile devices, will experience problems adapting to 1.1. Worse, every client is bound to a limit of 100,000 authentication tokens (or 100,000 users, but some people have more than one account) before requests must be made to Twitter staff for more tokens, effectively forcing a cap on the maximum number of users each client is permitted to serve.
Putting your account into protected mode, which only allows users already following you and users whose follow requests you approve to read your tweets, is a useful way to preserve your privacy. However, it will not allow you to interact with users not following back, unless they send you follow requests or have a non-Twitter means of contacting them.