I don't usually have a problem with comment spam.. I delete the few that manage to get past the filter. I just got a spam message apparently from a previous legitimate commenter (Mr Peters, I didn't know you'd taken up trying to sell little blue pills). The comment was 'no problem....', but on the last dot there was a link to a dubious site.

Nice try! Too bad it was spotted

By the way, I find a combination of the checkbox in the comment form (no other blogs use it as a captcha so I figure its safe), limiting comments to 2 links maximum, and the list of banned words in WordPress eliminates 99% of comment spam