Barry,
Got rid of these guys...
Scott and other Mods, as far as banning goes, I think it's perfectly acceptable as long as the IP's originate outside of westernized countries, as that is where the majority of spam comes from...
However, the guy that I just deleted and banned, 'fat loss fitness info x' came from, 92.21.33.186, which is an IP from the UK, handed out by 'opal telecom' - a large ISP providing to both business and residential customers in the UK, and is probably a dynamically assigned IP, which will eventually make it to another user, so therefore should not be banned...
Additionally, it was probably just a jumping point for the real spammer, who is likely using a computer that was infected with a virus as a stepping stone. This is what makes these sorts of things so difficult.
A modicum of research should always be done to determine where the spam is coming from before banning IP's from a forum, or legitimate users may end up not being able to access the service.