I stopped believing NEW, and the most recent troll, some time before they were 'outed'. I just really didn't know what to do about it, so I backed away from their threads.
Besides glaring inconsistencies, the biggest red flags for trolls, I think, are the fact that they always seem to post about 'hot button' topics. For example: MILs overstepping boundaries, people trying to 'test' their allergies, outrageous registries, pregnancy dramas, and anything that sends a person into 'mama bear' (ugh) mode.
Another thing is, they always act incredibly graciously and stoically in any given situation. Even ones where a real person would have long since stopped posting on eHell about it, and sought professional or legal advice.
Oh, and then there's the timeline thing, and the 'my entire life is a drama but I bounce back amazingly quickly' element.
The tricky thing, of course, is what to do about it. It does make me cringe to see people being taken in, but I never want to say anything because I have that 1% of doubt. Also because we may never know the truth, and I don't want to start an angry backlash against myself if I PM someone saying, 'hey, do you think so-and-so is a bit suss?' and *they* think I'm just being nasty and suspicious, KWIM?
This thread is, therefore, very enlightening.