I think the closest we ever came was that one kid (Lil-something? I don't remember any more-) who screwed up one of Ukase's MO runs by turning and running down the bomb hall when we'd all asked him to stay back. He claimed it was accidental at the time, but I'm not sure I believed him. I mean, seriously, that's some MAJORLY bad navigation if it really was an accident. <_<
Otherwise, we had our share of people who goofed up, or didn't read instructions... but I can't think of anyone who was actively griefer-ish.
Ah...that night. I can honestly say I've been more ashamed of myself than my knee-jerk reaction to that incident - but I sure wish I wouldn't have reacted like the game might end and some people might not be able to get those badges... oh wait...it did end! lol - of course, back then it never occurred to me that the game would end, but man, I sure acted like it would. Maybe this next time around I can try to not be wound so tightly.
The character in question was called "lil ole me". I think I've even seen his real name in one of the CoH FB pages. Honestly, I don't think he was a griefer - just someone prone to more errors than most of the other people I teamed with.
You can bet your 2nd to last dollar, I'll be leading those UGT's again if we get the game back. The first Friday after the game restarts - presumably after Noy's MSR.