I name-changed for some advice and was called a troll.
It's not nice, to be honest.
And it was a fairly bland thing I was posting about - I only name-changed because I know that friends - who knew about the issue I was posting about - would quite possibly link me with my posting name, and I didn't want that. I like to be able to post with a bit of anonymity.
I really do recognise the scenario described by Luggage.
A "popular and well-known poster" came onto my innocuous little thread and just pissed all over it - for lols, I guess, and I think other people assumed that she "knew" something they didn't..
I had a lot of p.m.s sympathising and offering advice off-board.
It's amazing how much I still loathe that poster, though.
So, in short, I tend not to troll-hunt myself. If I'm suspicious, I contact mnHQ.