How are these clowns getting on the forum anyway? Do they pay full price, or can just anybody write into the forum without joining and paying the up front cost? If they pay full price you could just throw them off the page and keep their up-front money. Another way to solve the problem could be to pay a bounty to members (funded by siezed up front money) if they find and report these usless advertisements. That way you wouldn't even need to find all these non-related adds.
If they are not paying up front, like everbody else, I can see why there is such a huge problem. There are now forum threads that are filled with as many superfilous adds, as ligit guitar entries. This is really getting out of control and it will eventually make the forum ever more useless swapmeet of free advertisment. That would be a shameful situation.
It is hard enough for people to learn guitar today. As Jeff has pointed out, there isn't a lot of guitar players around any more, and finding support is much harder than it was when I started decades ago (and most everybody I knew was an aspiring guitarist). Don't allow this forum to sputter out because of endless usless adds for term paper pimps, get rich quick schemes, Nigerian princesses, and other non guitar related crap. One need only look at all the people who find guitar related answers on the forum, to realize the scope and real danger of this problem. I, for one, would really hate to see that happen.
Sno - maybe I can find a Memphis manbo (voodoo priestess) to send some bad juju their way ;)