google has data from lots of other sources too... toolbar, adsense, adwords, api checking, backlink sources.... SEOs hand all of this info over to them.
I don't think that google is using this info to penalize SEOs. Think about this. If someone is working really hard to get a site up then that site would have to offer something of value or it would not be worth the SEO's time.
IMO, google is starting to count links and onpage SEO elements less and placing increasing importance on unique and non repetitious content. That is why you see all of the giant travel sites with duplicate textblocks and repetitious pages dropping from view.
* "It's not the size of the dog in the fight that matters, it's the size of the fight in the dog." Mark Twain
* "Free advice isn't worth much. Cheap advice is worth even less." EGOL