When I used Google AdWords, 30% of the clicks came from Google "content partners" which where nothing more than link farms. I'd say that was a significant source of revenue for Google... So much so that Google even put up its own parked domain service to further its profits.

If Google was "good", they would have either got rid of this 8 years ago, or never got into it in the first place.

Don't underestimate the amount of revenue Google generates from fraud.