If we could trust common and popular ad networks, that'd be one thing. But considering how many, like Google's, allow scammers to insert whatever Javascript they want, to load content from wherever, to be used to push Trojans and phishing sites, we owe them nothing.

I have no problem loading ads to support sites I like, but I won't because the amount of memory and CPU they require is ridiculous, and none of the advertising networks make a point to punish scammers.