I think the quality of your site content also influence
Pr.Google has said repeatedly that they will find a way to penalize sites selling links maybe it was not the everybody keeps calling it and they were actually serious. Paid links are the obvious culprit, though it’s an interesting list of sites.Paid Linking,Mass Linking are the main reasons that Google change the page rank.If Paid Linking houses use page rank as a pricing metric, then eliminating or devaluing page rank will devalue paid linking.Thanks for the time.