My realm forum is 99% trolls.
In any given thread, the same 3 people show up, including 1 person who spends an extra $15 per month for an account just so he can troll the forums, as his main account was banned for trolling. Every. Single. Thread. Someone may try to start a normal thread once in a while, looking for a guild, a pug, what have you, but it always ends up degenerating into some sort of joke/meta joke back and forth between maybe the 15 people who browse the realm forums on any regular basis. Every other thread is started by the trolls for that exact same purpose, because maybe they're too impatient to wait for a thread to degenerate on its own.
And you know what? I really don't mind, at all.
On any given realm, even the ones that are relatively troll free, only a tiny percentage will check the realm forums on any regular basis. Anyone posting on it for a useful purpose is betting on that percentage is enough people to maybe fill a prospective raid, or find a buyer, or what have you.
On my realm however, that number is so small, it's not even worth trying to post on the realm forums for any useful purpose, no one will ever see it. It's a vicious system, really. No one posts on the forums because no one checks it, and no one checks the forum because the only posts are from trolls.
Do the trolls contribute to that somewhere? Sure, but without them, the forums would be completely dead, as no one posts more than the trolls, and there will be no humor or entertainment in the posts.
Thus, on my realm forum at least, I gladly feed the trolls.