I think I understand what you mean.
There is a way to force new members to verify their account with a code sent through email. That usually deters spammers since they don't normally use valid email addresses. Unfortunately, other members have complained that registration was too difficult with that activated. Also, blocking Guests Posting does limit the potential of new visitors getting active. Until the new forum starts getting recognized more, I'd like to keep things open to encourage new users.
At this point, as much as I hate the spam, it seems to be relatively limited. I've only seen a few spam messages at the same time at most, so between me, TylerChuit, and Wyldwing (both Moderators) it seems to be under control. There was a point last year where there were around 10 new spam messages every time I logged into the site. Hopefully it won't get that bad again, but I will definitely block Guest Posting if that happens and force email validation for new accounts if it starts getting that way.
In the meantime, I have been censoring words and URLs so that the biggest offenders (image posters), do not get to share their teasers here. Sorry about the inconvenience.