A reason I heard was for Infamous. He said he HATED the entire game simply because Cole's pants made a squeaking sound when he ran. O_O The sound was actually rather subtle. So hating it is like hating your own pants because of the brushing sound they make with every step.
My reason for not liking a game: Well not I won't necessarily hate a game but I hate the result. I dislike big ultra-hyped franchises (Halo, Gears of War, Call of Duty) because then when a new unrelated game comes by with similar elements in story/gameplay, too many people, including fanboys/girls, will go on and on, back and forth on which game is better, and blah blah blah.
*sigh* I will never be able to play a cover-based shooter or FPS near others without hearing: "Not as good as CoD" or "Hey, that's ripping off Gears of War!"
Really? Can I not be allowed to enjoy a game in the company of others ever again?