Originally Posted by Yo Adrian

That's true, actual penalties could result in opening up the door for negative SEO, which is why Penguin normally only devalues the link value that passes through low quality and over-optimized links. And this is why guys with a lot of these low quality links lost their ranks.. the link value they used to have was removed.

Negative SEO is a different topic altogether.. and for the most part it's a myth, no matter what you read around the web.

If your site is strong, meaning you have content and good links and Google trusts you, than getting blasted with shit links isn't going to hurt you. Google's filters are just going to kick in and remove the value (negative or otherwise) that would have passed through them.

But if your site is weak or new or not yet trusted, than negative SEO can hurt you, because you don't have any other value to help insulate you.