Hmmmm! Food for thought, I have not been swamped by Google spam, but have purchased AdWords and it seems to be working quite well.
I made a decision based on costs and ROI that online advertising would give me a competitive advantage. (but not for long)
It all comes out of my advertising budget, so i am sorry to say that my local paper is missing a fraction of my ad spend
As for google "preventing individual Realtor sites from ranking well" I seem to agree, in my local market the biggest real estate websites that represent all agents get all the good placement, and now due to competition between them they are starting to move to pay per click also, forcing bids higher