First off, shitty content sites don't sell ads directly (generally) anymore than good content sites do. The ads come through a network like AdSense which means

First off, shitty content sites don't sell ads directly (generally) anymore than good content sites do. The ads come through a network like AdSense which means all that will result in is the shitty content site getting a lot more money. Second, it won't ruin online advertising if lots of people do this. At the end of the day all ads are converted to CPA and bid on accordingly. It's the only metric advertisers care about. They pay by CPM or CPC, which you can game by refreshing the page a bunch or clicking the ads, but the advertiser's cost will just adjust until they're effectively paying the same CPA. For instance, if half of all clicks suddenly become fraudulent, bids will decreases such that CPCs drop by half, resulting in the same amount of money changing hands. The only real problem with click fraud is when it is applied independently to one advertiser but not the ones he's bidding against. For instance if a bunch of people click AT&T adds fraudulently but not Verizon. If the click fraud is spread evenly throughout the market it has no effect.