I don't have one of these sites but I do own a relevent domain name and was wondering... When you first start out, how do you get people to put their ads on them if your traffic is low to nothing? Do you market your site through paid advertising first? Do you find some advertisers will buy space on your site regardless of hits? How do you get advertisers?
I don't think there are many companies that will purchase ad space (unclicked) on a site with no traffic. Maybe I'm misunderstanding you.
Unless you have a good Google Page Rank then 99% wouldn't pay to be listed on a milliondollar clone. These sites generate no traffic, as the only people visiting these sites are webmasters. Waste of money IMO.
Trafic is basic. and the core value, you visiter in high level, your website is rated by the ads. I think so!
The band wagon for this sort of idea went quite a long time ago I'm afraid. You won't be making a million from this. Sorry.