"Troll infested" just means it's a place where there's a lot of people who post nothing but crap to get people riled up, many of these people are repeat offenders and come back with new accounts because they're that sad. "Troll-like" means something like what you PMed to me in the first example, where it could be taken as an attempt to get people riled up. Some trolls try to be more clever with their attempts to cause chaos and will bring up controversial topics while acting like they just want a discussion in an attempt to anger people and start problems.

A troll is just someone who tries to start fires, basically.

A metaphor perhaps will help? Imagine someone starts an actual fire - they enjoy the panic and destruction it might cause, so they do it with intent. Firefighters go put it out. While they're putting it out, the same fire starter and/or a new one starts another fire. Firefighters go put that one out too, but the fire starter is already working on yet another fire. That's essentially a troll vs moderator relationship.