Lately, I’ve been seeing the same thing Alex has—comment spammers using pingbacks from splogs to evade most comment spam mechanisms. In particular, I’ve been getting a lot of spam from the maxblog.eu domain; tonight, I explicitly blacklisted this domain all over rmfo-blogs. Looks like Spam Karma 2 [at 2.3, anyway] sees the positive pingback, adds the +4 Pingback Bonus, and is happy from there. [I can't tell whether it ignores the blacklist at +4 or not; I thought it was, and then I checked the last maxblog.eu spam I just deleted, and it was prior to my explicit domain blacklisting.] Of course, I’m not happy with the spam, but hey … I can delete it pretty quickly. But like Alex noted, it’s a pain, and hey … isn’t that why I grabbed SK2 in the first place?
Let me address two potential objections before they arise: yes, I’ve contacted Dave about this [but admittedly just before writing this post, so he hasn't had any time to respond], and no, I don’t like running Akismet, even though I get how it’s designed to leverage network effects and all that. Man, I just don’t like depending on centralized stuff, and yes, I know that comments get processed on failure. I’ve thought about running Akismet and SK2 as a belt-and-suspenders approach, but honestly, SK2 does such a damn fine job 99% of the time that I don’t feel the need.
I guess the comment spammers weren’t content to ruin trackbacks only, eh?