In two online studies (total N = 1215), respondents completed personality inventories and a survey of their Internet commenting styles. Overall, strong positive associations emerged among online commenting frequency, trolling enjoyment, and troll identity, pointing to a common construct underlying the measures. Both studies revealed similar patterns of relations between trolling and the Dark Tetrad of personality: trolling correlated positively with sadism, psychopathy, and Machiavellianism, using both enjoyment ratings and identity scores. Of all personality measures, sadism showed the most robust associations with trolling and, importantly, the relationship was specific to trolling behavior. Enjoyment of other online activities, such as chatting and debating, was unrelated to sadism. Thus cyber-trolling appears to be an Internet manifestation of everyday sadism.Here's a popular press description.
A few comments. We should be careful. I mean something like this confirms what most of us suspect about our rightwing ghouls (including the parliamentary trolls in the Harper gov't) and shows us the best thing to do is not engage. There's really no rational argument to make against psychotic sadist.
Second, this isn't confined to lunatics on right. I dare say there's a few so-called progressives who might fit some of these descriptions, particularly those who abuse discourses that foreground individual identity or identities to the point where they dehumanising and humiliate others.
The lesson? Obviously, do not feed the trolls.