I think it largely depends on the industry you are in. The important thing to remember is that SEO is a long term strategy and therefore a long term commitment.
Google is always looking to refine its searches and it will get to all industries and those who are spamming will eventually get penalised. As Penguin 2.0 has only just been released, give it a few days and you will see the true effect of it. Keep the faith (even though its hard to sometimes!)