okay, here is my thought for this one:
Both the adultxxxdomains.com and the
http://www.caribbean-poker-stud.com/ domains are on the same host. I would bet you that they either have an IP address in common ( you might have their old one, example) or there is a funky dns issue that is sending googlebot to their site when it tries to index your site. Thus, it gets the IP, comes back with the poker domain, and away you go with backlinks up the ass.
Problem is none of them really point to you, so you don't get traffic. You also probably can't trade this PR, because google is looking at the cache of the other site for content.
Alex