The Washington Post has an interesting article about online trolls. After describing trolls as disruptive users, inclined toward personal attacks, the article describes their posting patterns:
... Those users, they found, tended to focus their comments on a small number of stories and were more likely to post things otherwise irrelevant to the overall conversation. Trolls' behavior also tended to get worse over time, according to the researchers -- and they were generally successful at getting a rise out of those in an online community.
...Unsurprisingly, research suggests these uncivil commenters tend to have some pretty dark personality traits. Research led by University of Manitoba graduate student Erin Buckels published in the journal Personality and Individual Differences last year found links between online trolling and narcissism, Machiavellianism, psychopathy and sadism....
Peterson, Andrea.(2015, April 22) Scientists have figured out how to tell when someone is an online troll. The Washington Post http://www.washingtonpost.com/blogs/the-switch/wp/2015/04/22/scientists-have-figured-out-how-to-tell-when-someone-is-an-online-troll/?wpisrc=nl_headlines&wpmm=1