Well, speaking as someone who (ahem!) does MySpace marketing for bands...
Yes, there are a LOT of bands who really, really abuse MySpace. I, too, absolutely loathe comment spam with huge graphics that eff up my personal page, so I rarely inflict it on other people when working for a client. I'd far rather use the filtering features MySpace has in place (e.g., the Google keyword search, the MySpace "filter by music interest" search... but a lot of people running band pages don't even know those features exist.

Also, a lot of times if you're using friend adding software, depending on which prog you're using, it's not really possible to either (a) look at someone's profile before adding them or (b) see that someone does not accept requests from bands. You can sometimes click "Cancel" if you're VERY quick, and I do try to do this, but every so often one is going to slip through. I try to make a note of the person's display name and delete the friend request from my pending requests (something else a lot of folks don't know they can do), but again, one will slip thru every so often.
I was just talking about this with a new client the other day - that it's entirely possible for a band to have too MANY friends and for those friends to be completely useless if they are not accurately targeted. This client is going to be mounting a major US tour in the spring of 2007 and I'm already thinking about what's going to be the best way to get him friends in each city who MIGHT ACTUALLY COME TO THE GIG. Sure, I could go "Find me all people within 50 miles of Cleveland between the ages of 21-100" and end up with 50,000, but would 5% of those folks even consider buying a ticket? Of course not. So you really have to target more narrowly than that.
So for anyone running a band MySpace page, I'd seriously suggest investigating the search options MySpace has available. And put some thought into your search string. Generally speaking my sites seem to have a pretty high acceptance rate (80-90% most days) so I guess I must be doing *something* right!