We are experiencing problems with spam on the Battle Grounds forums as well, and one of our moderators had this to say:
I’m not sure if anything can be done to prevent it, but here are my recommendations to the general readers of this forum: Don’t open the topics, and don’t reply. I don’t want to see those topics viewed by anyone other than a moderator. The topics are easily recognized. They all sound completely unrelated to anything you would expect here, and often the topic names clearly reveal themselves as selling stuff, or dealing with porn, and they all use a happy smiley face. Again, don’t look at them.
Moderators will IP ban (some of them have at least two memberships), and delete topics on sight, to minimize exposure.
If anyone knows how to deal with it more efficiently, tell a moderator.
Might as well try it, we don’t have anything to lose.