I know what you mean, the more traditional spam can be found from the same link -
http://www.wildaboutbritain.co.uk/fo....php?do=search - by adding a 1 in the 'greater than' and a 2 in the 'less than' post count boxes. Hundreds of results and many of them with people joining then posting once with a link to their site, then disappearing again.
This isn't so much of a problem as I've added code to block the search engines following the links, but before that I'd gone through hundreds of similar post and removed them manually. Since then, the 25 post limit has certainly helped out a lot too.
Stu