Many of these people are obvious. I'm not going to name names, but they are the ones I call "thugs" or sometimes "new thugs" -- they pretend they're aren't sitting on the fence, that they aren't hob nobbing with the trolls, that they aren't exhibiting nasty troll like behavior themselves much of the time, that they aren't wasting time and spreading negative energy by insulting others.
Here's a bit from UFO Mafia:
Bottom line is I’ve run into many a notable UFO researcher who just doesn’t fit into the equation of wanting to solve the mysteries involved. Instead they gripe, make bizarre accusations, try to publicly invalidate another person’s reports and theories, just real underhanded tactics one would think would come from the skeptics and debunkers.