Google Penguin 4.0 algorithm update took place in September but it is completely different comparing to previous ones. Previously, if your website has many spammy links it might not be penalized so hard like it was before - vanish from Google's index for a long time. Why? If you will remove those spammy links Google's robot will re-spider your website and re-index it almost at once and this is because Penguin 4.0 runs within Google's core now. To avoid all troubles is to concentrate in building of quality links and content. Yes, that's the best solution but it takes time...