Me and Phill on another forum have discovered that replying to spambots indicates to the spambot's operator it has an audience and will attract more of them to the forum, in the same way of replying to a spam email (even if it's with &%^$ J00!!!11) encourages more to fill up your trash bin. Even opening the thread has an effect as they watch the 'thread views' number with their 1337h4x0r programs.
Disabling guest posting didn't work too well as they just went through the sign up procedure and posted. Quite annoying really.
Thought you guys might like to know.
Resident tank enthusiast. See me for racist and opinionated storytelling and vaguely accurate historical tank warfare-themed rants.
The mods haven't been thorough enough in vetting the subscriptions, then, or there simply aren't enough mods for the volume the forum takes. I've always made as many people as I possibly can be mods on mailing lists I run. In short, nuke the site from orbit, its the only way to be sure.