I think the reasons for buying the site depend on your point of view - to you, it might be worthless (as you suggest), however, to others it could be extremely valuable.
consider the same argument for any website....i.e. why would www.diy.com be of any value to anyone?
The answer is simple; Hits. The whole purpose of many websites is to get as many hits as possible for whatever reason (normally to sell stuff).
It is a guarentee that SPAM IS going to get lots of people going to that page in search of information on what the song is about. If you dont believe me, then checkout the counter at the bottom of SPAM (which has nothing to do with me).