I think Google is to blame for this- MFA trend. And the problem is that once they approve your "submitted" site for Adsense, they will then let you put the same adsene on any other site you may own without approval. This leads to people creating spammy sites just to try and generate adsense revenue (same probably goes for other ad networks too).
The health wiki that was created by Frank Schilling doesn't seem to be spammy at all, and in fact seems to be a real resource. Not to mention I couldn't find a single ad on the site (maybe I didn't look hard enough).
Blogging is the biggest problem now, where the majority of blogs seem to be splogs (spam blogs) designed to attract organic search traffic and generate adsense or affiliate revenues.
The other problem is that Google is making a lot of money from these spammy sites, so its not in their best interest to eliminate them - until or unless they start to damage their reputation as being an efficient search engine (which may happen).
As google adjusts their algorythem, so will the spammers. So all it does is create a cat and mouse game that never ends.











