I got a relatively new site that has gotten penalized or banned just as it was starting to perform because it somehow got added as a site wide link in a site that seems to be also selling links at the footer of all their pages and linking to text link selling companies. It isn't my best work though, with a lot of duplicate content and few quality inbound links. I just created it to test the waters. Still I find it strange. I'll probably have to check my pages and see if I don't also link to a banned site or something.