What genres do you absolutely, positively, unequivocally suck at playing? For me, it's platformers and fighting games. I'm awful at platformers, especially 2D ones, and I often find them exercises in frustration moreso than enjoyable gaming outlets. As far as fighters go...I just plain suck at memorizing and pulling off combos and usually just find myself spamming the attack button.
Up until last year, I was terrible at online first-person shooters. I've gotten much better, though. Probably fighting games. The effort required to memorize combos is too much for me. xD
Platformers. I am so bad at platformers. It's embarrassing how bad I am at platformers. It's weird because I'm good at timing in any other genre but if you have me jumping from one ledge to the next as the only gameplay parameter, I'll miss it SO often. I don't even know what it is. Maybe it's that I go into it with the mentality that I'm going to miss every jump so I do but that seems a bit ridiculous because I go into shooters expecting to die over and over again and I do fairly well with those if the difficulty isn't too high. I don't get it. I say I suck at fighters, but I'm not THAT bad at them, I think. I don't play them a lot because I don't overly enjoy them which is probably why I don't feel like I'm good at them. But looking back at it, I've beaten people at their "own" games several times in the past before when it was my first try. :P Oddly enough, when platforming is added into 2D fighting games (Brawl, etc.), I can actually hold my own fairly well. (Mind you, most fighters I end up playing are very forgiving to people who button mash.)
I guess I'm bad at MMO's since I've never played one (and don't plan to). I don't want to come off as being cocky but I'm good at everything really. Platformers, RPGs, JRPGS, Third-person shooters, FPS's, action-adventure, puzzles games, simulations, fighters, beat-em-ups, racing games. Of course I'm stronger in some genres than others but I wouldn't say I suck at anything. Oh wait! I just remembered! Sports games! I'm bad at sports games!
In general, I really was fine at most types of games, given a bit of time to get used to them. However, I am officially terrible at sports games now; primarily Fifa. I just... I suck. I don't understand how you're actually supposed to be able to score, it just... no. Also I'm fairly mediocre at racing games now too. Otherwise I'm pretty all right, though :P
For me it's mostly FPS. I just don't have the reaction time to be able to shoot someone before they shoot me. Plus most of the time it involves multitasking where you have too run and shoot and turn and do everything at once and I'm just no good at any of that. I'm also not very good at most sports games but that's mostly because of lack of interest.
Not great at fighting games or racing games. :/ I was really good at Blur (my favorite racing game ever) and I'm good at Mario Karts, but anything more realistic/serious and you can count me out. Haha.