Jeremy at WebproNews has an interesting article written after meeting some comment spammers.
‘One of the comment spammers asked me: “You know why we spam blogs, don’t you?” And I knew the answer. They do it because blogs are easy targets and because, just like e-mail spam, it works….
Then a partial solution is fairly clear. I’ve heard and seen others discuss it over the past few months. The search engines needs to be smarter about reading and indexing content.
Read more at Some Comment Spammers Have Blogs Too