As you know, I’ve been reviewing tons of websites that have lost Google traffic lately. Most of the reasons that the sites lost favor with Google have been fairly obvious (to me) – especially the sites that have seen steep declines. Most of the reasons include any combination of:
http://www.sitepronews.com/2012/07/26/what-to-do-if-you-receive-an-unnatural-linking-message-from-google/