Blog Spam I Don't Understand

A couple of days ago, asisaid was hit by blog spam (something unusual for my blog, for whatever reason). Most of it was at least semi-explicit, but it also had a peculiar quality to it: none of it seemed to actually point to anything. Several of them seemed to include phone numbers, but with the wrong number of digits. When I looked in my database, the poster left neither an e-mail nor a web site in the contact information. This left me wondering: why spam a blog if you don't even link to a product or service?

Is this just the twenty first century equivalent of graffiti?