Hi there.......
Google penalties are primary method used by Google to control the webmasters and prevent them from using spam techniques to rank high in SERP. The confusion over Google penalties is that not knowing what will cause a penalty. The fear of uncertainty is due to the fact that Google algorithm keeps on changing time to time.
A Google penalty can be decrease in page rank, sudden drop in ranking in SERPs. The ultimate penalty can be complete ban of a website from Google search engine listing. Sometimes ban on host results in penalty to the clients’ site.
Google can raise a penalty for violations of its terms and services (
http://www.google.com/terms_of_service.html). There is a set of guidelines with many explicit rules provided by Google for the webmasters, which are meant to be followed (
http://www.google.com/webmasters/guidelines.html)
Your expert views are solicited..