As the web evolves those guys are getting more and more sophisticated (read "obnoxious").
More ads with audio you can't shut off, more sites with ads which much be viewed in toto, and on and on. They've figured out how to do it.
I met a guy who makes a living by getting hits on the ads placed on his Youtube site. He gets a certain amount (he wouldn't tell me how much) for every hit, and more if the ad runs to completion.
On the one hand I can't blame them and on the other I resent it. I'll worry about consistency later.
Pure crookedness such as you encountered should be prosecuted, however.