I get an astonishing amount of comment-spam, nominally about dresses - wedding dresses, prom dresses, square dresses and how to fold them, and so on. None of it ever appears so I don't know why they bother, but simply deleting it all from my email queue is becoming ever more tedious. So I've changed one setting - old posts are now closed for comments after 60 days instead of 360, in the hope that at least some will now bounce off.
Oh, and a corollary of all this is that I'm far less careful than I used to be about wading through "comment requires moderation" emails. If you've got one that's stuck, mail me separately.
Maybe you could ask scienceblogs to install some sort of captcha program.
http://www.captcha.net/
Also scienceblogs could use Akismet to filter out a lot of the spam: http://akismet.com/
[It already is -W]