The "shady" ads are usually adwords ads - yes, adwords allows some shady ads, but they also include lots of legit advertisers too. Yes, the parked pages are no

The "shady" ads are usually adwords ads - yes, adwords allows some shady ads, but they also include lots of legit advertisers too. Yes, the parked pages are nothing but ads, but users who land there are looking for an escape and a surprisingly high number click on the ads. You can find out more from Marchex which is a public company (ticker: MCHX) that runs a large domain portfolio (since it is public, they disclose lots of info).