> That said, click fraud has really burned a lot of advertisers.

THIS

> That is why advertising on content needs to shift to a performance based model,

As someone in the ad biz,it's something hard to do.You still need ways to track(I understand people don't like it but...) accurately where the traffic comes from.We really need innovative tools in that domain!

Finally,I think the biggest disappointment in web marketing comes from the (un)ability of social medias to really influence sells.FB and co ad services are way worse than classic web advertising.It's borderline scammy.