To elaborate, if you think (or know) that someone is a troll, ignore them. Replying to a troll's post is "feeding" the troll; it just encourages that person to troll more since they're usually seeking attention. Ignore the post, but reporting the post or member to a moderator is fine.
I disagree to a point, at least concerning Ehell. Our trolls have typically been the "A Horrible Tragedy Has Befallen Me" type, which garner tons of attention, replies (and usually lots of PMs to the troll), and support for the troll. I, for one, appreciate when other Ehellions have asked the OP of these threads questions/pointed out incosistencies politely (& the Dame has given approval for this), because A.) it stops from worrying about the OP for a false reason, and B.) I don't have to continue to be taken for a ride by the OP.
However, in a thread where I suspect the OP may be embellishing, I typically just ignore it if it's not
the type of thread where tons of other posters are worrying about & offering support to the OP.