Every time I come on this site, and hit "new posts", one seems to find a new batch of spam posts for wowgold, porn, or whatever. I always report these, and the Admins/Mods here remove them with commendable speed.
However, this site clearly has real problems with spam, and the best protection from it, I've found with sites I'm involved with elsewhere, is to stop the spambots and human spamborgs from registering in the first place.
I'm very surprised to note that the site doesn't seem to have CAPTCHA image verification turned on for registration. This can now (alas) be defeated by the spammers, but there are advanced CAPTCHA hacks and alternative strategies, e.g:
You might not want to have a discussion here, but I'm a bit surprised more isn't being done to fortify the "exterior walls" of the site?