MW and MW2 have pissed me off pretty much more than anything else in life. I broke a TV remote control into pieces and dented the wall of my living room once (with said remote) while playing MW. I'm very competitive and really hate dying. I haven't played either game in months, which is a shame because I find both really fun, but I don't like raging. I really wish I took it, and all games, less seriously, because it really ruins the fun.
Toward the end of my playing, I would only play certain maps and usually played as a sniper as that seemed to get me killed less (plus it's pretty fun.) Probably the biggest reason I didn't get Black Ops is because I read that sniping wasn't as effective.