Good luck with fight back but i'm not sure of it will help at all.
Mostly of them use proxy servers, they never take a look into any forums because they use automatic submission software that allow them to submit post to *000 forums using weakness of forums (phpBB, vbuletin, Invision Power ***rd etc...).
The best thing is to install some mods that will fight against it.
Because i run phpBB can not help a lot with vbulletin but they have for sure some mods that will help fight back.
[URL="http://www.proxyblind.org"]Free Proxy[/URL] | [URL="http://www.proxyserverprivacy.com"]Proxy Server[/URL] | [URL="http://www.ipaddresslocation.org"]Ip Address[/URL] | [URL="http://www.proxyblind.org/list.shtml"]Proxy List[/URL] | [URL="http://www.bearplanet.org"]Polar Bear[/URL]