There are no “rules”, only “guidelines” when it comes to search engine optimization. This makes it very difficult for webmasters to understand what constitutes search engine spam.
Danny Sullivan, editor of Search Engine Watch, thinks its time that search engines start to come clean with their policing policies. He believes they “should agree to publish lists of companies they’ve banned. That would help consumers seeking SEM firms to understand which to avoid.”
A good idea that likely won’t happen. So what can you do to protect your website from being banned? You can get professional advice from a search marketing firm who understands the guidelines and works to insure that they are not violated, or you can live by these words:
“Webmasters who spend their energies upholding the spirit of the basic principles will provide a much better user experience and subsequently enjoy better ranking than those who spend their time looking for loopholes they can exploit.” – Google