Users arrive on such pages by following an outdated link, or by accident, and are presented with nothing but adverts on a page with no content. Worse, it has brought about a whole parasitic industry of people trying to snap up expired domains, and then replace the previous content with something of no intrinsic value.
I wonder if the ultimate conclusion is for website owners to remove their own content, 'park' their websites and rely on residual links to send traffic. Click through rate wouldn't be a problem as the only other way out is with the 'back' button.
Having discovered that I was paying for clicks from such pages, I have decided to stop running adverts until I can be sure this is no longer the case. I know this has been discussed before, but Google, do you really think this should be part of your business model?
I have beef with adwords when they allow parked pages advertise, and do arbitrage on the keywords where i am biding. Why are they not getting nuked with the quality score?
Something that has bothered me for a while is the question of why Google allows Ads to appear on parked domains.
Note: I saw a recent WebmasterWorld post that AS for domains is closed to new sign-ups but can't find anything else on this.