What is the different agenda?

Also, I would think that Reputation is more suitable as you would be posting of the users (which reputation is mostly used for) instead of things relating to the forum itself. I understand that spam is a forum-wide problem, but it just felt like a better place to put it.

(Oh, and you can usually pick out a spammer easily by randomly going to any huge thread and choosing someone that recently posted. Most of the time, their replies are "redundant, generic and is a one liner")