Tried putting a nofollow link to some site in the template of your blogs/forums or footer of your html pages?

Many of the comment spammers look for "dofollow" links by checking a page to see if it contains "nofollow". I'm thinking if a page has a nofollow link somewhere on the page, many of the comment spammers will think the page comments are nofollow....I'm pretty sure most spammers don't check every link, but rather just search a page for "nofollow".