My recipe for getting rid of comment spam once and for all: Install WordPress 1.2.1 or later. Install ImageAuth hack Go to Options Tab. Under Discussion ensure:

I have been unable to submit a comment in a site with spam karma enabled. So I wrote a comment in the spam karma plugin site. Wonder of wonder's the spam karma filter trigerred again! And then it took me to a CAPTCHA plugin :) After validating it complained again by throwing me a beautiful looking sql script.

Lets start with a great story by Prescott in his book on consulting. "... My grandpappy used to tell a story about a stubborn cucumber. When he put it in the barrel, it looked around at the other cukes and was revolted by what had happened to them. 'Dadgum it,' he cursed. 'What's the matter with you guys? Have you no pride? No self-respecting cucumber would let himself get pickled without putting up a fight.'