I believe most of the spammers that hit CPF are humans, although there is one with an Israeli IP that I suspect is a bot. Either a bot or a very determined individual. There's an array of IP's with just the last 3 digits of the dot address changing. Since last November we've recorded over 400 hits from the addresses in 212.235.107.* The first few contained bona fide spam links. StopForumSpam has hundreds of reports from the same range. So I have a wildcard ban on that group.
Do you run the suspects email address through Google? That frequently will bring up a list of that email address showing at a list of other forums. The forums on that list are ones that allow guests to read the member profiles. I look at the referenced profiles and if they show things in the signature block that could be considered spam I take that into account.
This AM we had two that turned up in a half dozen other forums. I figure an IP based in India, with signature links to a Toronto Canada airport limo service placed on a forum in Germany that's all about bittorrent software might be up to no good. Especially when you can find the email address on several other diverse forums with registrations all occurring the same night. The other was planting cell phone service links on a variety of forums. As well both came up on StopForumSpam.
I do believe there is a mod written for the SMF software that will read your database. I haven't bothered with investigating. If I recall where I might have seen it I'll let you know. The SMF forum has loads of mods for their software. Things for blocking spammers using database info, as well as mods that will turn the first
X number of links posted by a member into a non clickable link. After
X is passed things go back to normal.
I find
http://en.utrace.de a handy IP lookup. It shows the IP location on a map graphic, plus will provide all the info about the owner.