[Mauzen]

Only checking for the number of posts will result in even more spam. There should be (maybe together with the postcount check) a minimum time that a user has to be registered in the forum, like 1 or 2 months. Most people that only register to the forum to spam their gf edit ad, will have to wait some time, and will probably loose the interest, as they see that noone wants to play their gf mode. Only good servers/owners will still be interested in keeping their server and posting ad for it after that time.
This would part the bad servers from the good ones, so there will almost only be good servers in the ad section.