Alternet has two really good articles on the behavior and psychology of blog trolls:
How Do Internet Trolls Justify Their Nasty, Misogynist, Life-Ruining Behavior? - and -
The One Psychological Characteristic That Online Trolls Tend to Share It's interesting that some bloggers choose to use many various identities (both male and female - sometimes conservative, sometimes liberal) when engaging discussions and end-up being banned all of the time. I've been on Disqus for over three years and have never been banned - even from Greta Van Susteren's old site.
I think the real reason for frequent banishment is because many think they're so witty and clever as to "pull one over" on other bloggers and that the other bloggers don't know who these trolls are using their plethora of identities. The term "sock puppet" is used for that account of this type blogger who engages in that type of deceitful blogging.
No one wants to engage in a troll like that. From a moderator's perspective, that type of blogger is a pain in the ass and really adds no value to the discussion other than to troll and looking for fights to pick.
Having a Disqus blog myself, I have had to deal with such bloggers as described above on way too many occasions. Disqus used to allow us to ban the IP address - which was preferable and eliminated the "sock puppet" resurrections. Now we have to play Whack-A-Mole every time these sh!thead trolls appear.
My Disqus blog has had many good discussions in the past and it is possible to engage in discussions as has been demonstrated. I get that some prefer nice, clean, responses like here on UBB, choosing to participate on different formats requires flexibility and adaptability, and I can see where a blog troll would find inflexibility to be a hassle - because where's the fun if you can't bait people for all to see?
