It's an infestation
A person who posts on a blog thread, in the guise of "concern," to disrupt dialogue or undermine morale by pointing out that posters and/or the site may be getting themselves in trouble, usually with an authority or power. They point out problems that don't really exist. The intent is to derail, stifle, control, the dialogue.
The key thing to remember is that they sow doubt among the undecided voters!
"But, but what about the caged children?" is an example. There are many insidious ways to manipulate people's emotions!
That is why they are dangerous.
The majority of what I've seen so far is what's called "LARPing"
That's when someone who wants to get karma on reddit for exposing how hate filled our platform is, so they make an account and post something horrible because they can't find it here otherwise.
They think they're fooling us but they make their arguments in the same delusional way that lefties argue.
Says the person with an offensive account name that was created 20 minutes ago and has said nothing but horrible things.
You're exactly who I was talking about.
Says the person who obviously feels compelled to attack our new platform.
See, your projection is what gives you away lefty.
Deport
It's called RoleCon, Roleplay Conservative
They like to spread F.U.D.
Fear Uncertainty Doubt
Usual story in both places. When Reddit started houndin' The Donald bad, I mean up their dom sub arse like rabid kinky Panda back where wonderful, great and even righteously dangerous real shitposters/autists still fight the good fight; muchly the scum, not the downvoted cream, floated to top.
Deport
?
Is that you concern troll?
Another form(and I think this is where the term came from) is posts like "Anybody worried about(insert administration member/policy?" I think it could hurt our cause...it was often used to foment infighting.
I noticed that you didn't put a period after infestation. Why do you hate grammer? [sic]
/example