Googles doesn't really say, and I believe they are caught in a tough spot - unable to create an enforceable rule. https://support.google.com/webmasters/answer/

Googles doesn't really say, and I believe they are caught in a tough spot - unable to create an enforceable rule. https://support.google.com/webmasters/answer/2648487?hl=en https://support.google.com/webmasters/answer/2648487?hl=en I actually think one of the things that stops competitors from buying poor quality links, is the fear that it might have the opposite effect. Google simply can't keep up with the spam that is created - so they are forced to take a moderate approach.