As a moderator I can add a little info here...
When someone reports a post, I get an email notification as do other moderators. When I check my email I will go to the linked post and delete if needed. I will then use a feature of this board to delete the user so that same user can never post again. There are several of us that are on at similar times. I know that John Boucher and Gary Vostol and I are usually on early mornings. (I get to work at 6 AM and John and Gary have usually done some clean up before I get on. They are on Eastern time.)
I alerted Brandon a while back that spam was at an increase. It seems that when he had released India as a valid area, the spam increased. India has FTC teams and we hope that FRC will start there as well. That was behind the decision to open up that area.
As to the spam itself, this is similar to junk mail. The people behind the onslaught work on what it will take to get some one to pay up. In junk mail, those folks believe 100,000 mailings to get ten or less customers is valid. Without moderation, we know the posters will begin to flood the forum on a logarithmic scale. With everything in place, we are seeing only one or two posts from each poster.
I also use a site for research if I suspect the user is valid. It is
http://www.stopforumspam.com. By entering the user screen name, you can see if this user has been reported and where the location of the ISP might be.