[tomlor]

I've seen some other pretty abhorrent behavior as well. The specific instance that comes to mind is an ad that would load all the resources and content of its click-through landing page into a hidden part of its own iframe. Then in the off chance you click the ad, your browser cache is already warmed and the resulting landing page loads fast. All of that for the 0.1% of us that click ads. It boggles the mind.

[jdangu]

That's not the reason, it's ad fraud. They are most likely paid on CPC (cost per click) and forcing clicks in a hidden iframe. Or they are "stuffing cookies" for an affiliation link, betting that you might buy on that store later on - and getting a commission out of it.