Spam bots usually target LJ help, yes. But not always.
There have been advertisments posted in Designer's cafe, as well as a few other places.
Maybe we should have a thing that blocks anyone with 0 posts to post a topic.
But then again, a lot of people who need help (with Myspace and such) would have to post in a few places before making a topic about their issue.
So idk if it would be the best idea. It would help get rid of spambots though.