1. Love for overly difficult games. While I don't mind games that offer different levels of difficulty, I dislike how people rate a game on how hard it is. I tend to play a game on the normal setting the first playthrough to enjoy the storyline (in the event there is one) and then look to reply it at a harder level (see Gears of War, Trails of Cold Steel 1&2, Akiba's Trip, etc.)
2. Hating on the PS Vita. Okay, I play mostly JRPGs and the Vita is loaded with them, but I always laugh when a person's main argument is that the handheld has no games for it. I tell them to ignore GameStop and do a little research. It's a very versatile device that has tons of games for it, not to mention loads of old PSP/PS1 downloads to be had. For some reason people love to target this wonderful device.
3. Anything Call of Duty past Call of Duty 2. I just don't get the appeal of endless number of releases that appear to mostly be the same. I guess the same could be said for most game genres, but my son loves these games and they all have the exact same feel to them. I play them so we can bond and share memories together, but the entire time I'm wishing he liked other games. He's only 8, so there's still hope he will like the games I'm into. If not, that's his choice. I see them as the FPS version of Madden. Every year a new one is released, but the only thing different is the roster and the graphics are slightly better.