Respawn positioning has done my nut in tonight. I think it was a fairly hectic edition of Ground War (this was just before Jin, 50! and Badger entered) on Estate which drove me to boiling point. I killed a chap in the basement/lower floor of the house at the top of the hill, only to be dropped some 5 seconds later. I swore I'd scouted the room before leaving, and the killcam showed me the person (who I had just killed) respawn directly behind me, across the other side of the pool table. I've never known it so ridiculously bad.
And speaking of ridiculous, I was with someone who achieved 39/0 earlier, and over FIFTEEN of those were from a chopper.