I want to like the idea of multiplayer, I certainly enjoy multiplayer with my friends but playing with strangers is the single worst gaming experience for me, at least as far as FPS games go. Worse than any Final Fantasy 13 cutscene or game breaking glitch on New Vegas. It seems to me that the majority of strangers I meet online just can't rise above using cheap tactics like camping a doorway on Blops with a shotgun like a little Derek Doorwatcher or shooting my horse on Red Dead Redemption's Free Roam while I'm minding my own business.
Also, children. I'm 24 years old, I'm far too old to be playing with kids. But games like Call of Duty are FULL of them., each and every one of them more ignorant and stupid than the last. To make things worst, I'm hassled by them even if I'm NOT playing. Me and my girlfriend were grabbing a bite to eat at a restaurant and sat behind us was a family with a couple kids who couldn't have been older than 8 talking and the kids were talking about unlocking the MPL and what their favourite shotgun was on Blops. I had to bite my lip so hard that I nearly drew blood.
Though maybe the real problem for me and multiplayer is that I'm a genuine misanthropist, I don't know.