What type are we working with? I see there are many?
Generally the first paragraph sums it up ...
An Internet troll, or simply troll in Internet slang, is someone who posts controversial, inflammatory, irrelevant or off-topic messages in an online community, such as an online discussion forum or chat room, with the intention of provoking other users into an emotional response[1] or to generally disrupt normal on-topic discussion.[2]
An this section subs it up pretty much.
Identity trolling
In academic literature, the practice was first documented by Judith Donath (1999), who used several anecdotal examples from various Usenet newsgroups in her discussion. Donath's paper outlines the ambiguity of identity in a disembodied "virtual community":[10]
In the physical world there is an inherent unity to the self, for the body provides a compelling and convenient definition of identity. The norm is: one body, one identity. ... The virtual world is different. It is composed of information rather than matter.
Donath provides a concise overview of identity deception games which trade on the confusion between physical and epistemic community:
Trolling is a game about identity deception, albeit one that is played without the consent of most of the players. The troll attempts to pass as a legitimate participant, sharing the group's common interests and concerns; the newsgroups members, if they are cognizant of trolls and other identity deceptions, attempt to both distinguish real from trolling postings, and upon judging a poster a troll, make the offending poster leave the group. Their success at the former depends on how well they — and the troll — understand identity cues; their success at the latter depends on whether the troll's enjoyment is sufficiently diminished or outweighed by the costs imposed by the group.
Trolls can be costly in several ways. A troll can disrupt the discussion on a newsgroup, disseminate bad advice, and damage the feeling of trust in the newsgroup community. Furthermore, in a group that has become sensitized to trolling — where the rate of deception is high — many honestly naïve questions may be quickly rejected as trollings. This can be quite off-putting to the new user who upon venturing a first posting is immediately bombarded with angry accusations. Even if the accusation is unfounded, being branded a troll is quite damaging to one's online reputation."