Anti-spam service advertising via spam.

Twice in as many days has a business called "spam blocker dot biz" left comment spam in this blog. This is not acceptable behavior. Why is it that newbie anti-spam businesses feel that spam is ok if they do it?

And to top it off, their business model isn't very good or original — it's just another challenge-response system. Also, I've already thought of two ways that spammers could game the system, although without seeing the fine details of how it works, I can't be sure.

And why is it that domains ending with .biz always seem so dodgy? It's practically gotten to the point where you can use .biz as a spam indicator.