It's a plague. There is nothing particularly worse about the spam situation on this site than on other sites. Look at the comments in Gizmodo and other Gawker blogs. That site is HUGE, and yet there's at least one "my sister makes $7843 every night on the computer" posts in every comment thread. Sometimes they last quite a while before getting deleted.
I've learned to ignore them and they don't bother me (after all, advertising is all around us and you learn to tune it out), however I'm at a loss to understand why the "boffs" as it were can't just write algorithms to combat forum spam in the same way they combat viruses, i.e. with a constantly updated database of spam definitions. We can install ad-blocking plugins on our browsers, so why isn't there spam blocking software in forums and comment threads?