I hate the thirteen-year-old boys who think they know about war, death, weapons, and combat because they can quickscope. By that logic, playing Skyrim should give me the ability to shoot fire out of my hands.
Hate anyone who measures the quality of a game based solely upon its graphics. So, there's CoD, Crysis, and Skyrim -- and everything else is shit? Say what with the what, now?
I don't get the hype around Halo. I don't hate it, I just didn't think what I played of it was all that and a bag of chips.
Generally I don't consider getting a game that has a less-than-good Metacritic rating.
I won't play first person games on console. Aim with a stick?
Hate those who do any of the following in multiplayer:
Rage quit over literally nothing;
Go AFK at the most hectic moment;
Trash-talk other players;
Team-kill or other grief play;
Run off alone and die to overwhelming enemy force, repeatedly, like that concrete wall is gonna crack if he just bashes his skull into it enough times;
Pipe what I will charitably call "music" through the mike channel;
Loudly proclaim that he knows the sole path to victory in the current scenario, attempt to boss everyone into doing things his way, then throw a fit when nobody does what he says.
In other words, I hate at least 80% of people in multiplayer.