aristotle - 6:09 pm on Sep 25, 2009 (gmt 0)
About a year ago I discovered that one of my sites had suddenly picked up several dozen backlinks from a very "bad" neighborhood. It's possible that a competitor created them, but I think it's more likely that they were created by an automated program as part of some kind of weird SEO scheme for those sites. At the time I was very worried that these links would hurt my site's rankings. But there was no noticeable effect, and a couple of months later those links disappeared.