The only SPAM we had was on the sites that Anon posters were allowed to use. We had it that way to make it easier for folks to post in those forums.
The Forums were Results, NORs, Find a Crew and Meet Someone.
For a long time there was no abuse, but sure enough it got pretty bad.
So, I deleted all data and started those Forums over fresh and now you have to register to use them.

Other spammers that have registered have all posts by them deleted in batch, and then are banned from posting.
Rick