Laws make you behave accordingly. I was reading a topic at webproworld where ignorance (some trick without purpose) could have attracted some penalty. Google (in general GYM, Google Yahoo MSN) laws differ from Land laws.
Land Laws : Let no innocent person be punished. Leave 5 criminals to save one innocent person. Every life is important.
Google Laws : Let no spammer (WWW criminal) go unpunished (or rank in SERPs). Let 5 innocent sites die while punishing a spammer. One site makes no difference.
Understand GYM laws and be careful with any spamming techniques. Ignorance is not innocence here. In case you are about to get a punishment please refer to this document http://www.mattcutts.com/blog/reinclusion-request-howto/