First it was Mozilla, then BBC & Now sprint has been hit by Google’s user generated content spam penalty. Mozilla was the first to get message from Google with user-generated spam on the site. This kind of spam is found on guestbook pages, forum pages, user profiles. This resulted in Google applying a manual spam action to the site. The entire site was not hit by spam penalty. Comment spam is one such spam area where Google is looking for UGC spam.
Then BBC was sent a notice of detected unnatural links. With such a big site like BBC & so many pages, it would be difficult to find out the spammy pages & remove. Sprint, the US telecom company has also been hit by UGC spam penalty now. Google usually applies Granular penalty to the pages
Google has said that publishers should talk to volunteers in the forums on how to avoid the penalty & also to overcome the problem. Google has 2 types of penalties. Manual & Algorithmic Both the penalties affect the ranking in the Google & also might affect traffic. Many sites have communities, forums & groups to discuss about the products, services & others. Google Groups is the best place to discuss issues related to UGC & overcoming the penalty.