They don't know when to stop
You know, when I added the guestbook to my site, I made a vow to myself that I wouldn't censor it.
But some idiots insisted on putting up totally unrelated entries about web outsourcing and such nonsense. I'm a web designer myself, why would I want to hire someone when it's hard enough to find work myself?
So, I decided to close down the guestbook. I don't want to have to censor the guestbook, and it would be dishonest to claim it was uncensored if I removed such entries. So there. 1:0 for the spammers.