zett - 6:11 am on Aug 24, 2009 (gmt 0)
I think the major issue for the OP is that the link is added automatically by the social networking sites in question. Then again, if the site owners run a fully automated site, how could they possibly check each link for its value? So what do they do instead to keep their site trouble-free with Google? They just define all user created links as "spam" by default.