What's the Point?

So, on a whim, I hit the "Next Blog" button at the top of this site. I did this a few times. What I encountered baffles me a bit.

Along with real blogs (oh joy!) I got whole blogs of SPAM. These records of advertising gone wrong have seemingly random letter combinations as titles. They feature "Entries" about all the stuff I delete in my Bulk Mail folder: Mexican Vacations, Erectile Dysfunction medication, Cheap perscription drugs sent right to your door. I don't get it.

This isn't new, but why spam in this form? Can't people do just what I did,hit the button again and leave the fake blog? Who's going to bookmark these sites?