However, if the advertiser is like the bulk of online advertising (e.g. one of the many for-profit online-degree-mills or someone pushing the latest weight loss pills) they tend to very aggressively optimize towards a desired CPA and eliminating non-converting traffic is always the goal. A better CVR creates happier advertisers which leads to higher bids & budgets and then higher publisher payouts.
There are brands / stores / products I've avoided specifically because of the advertising, whether it was annoying, disgusting, insulting, belittling, bigoted, or whatever. I've got several examples in mind as I speak.
The truth is ads mostly don't have value -- but the worse your product is the more you need ads.
Given that I have spent years working in the ad industry and writing ad servers, this is somewhat ironic.
I work in the ad industry, specifically real time bidding and I am thinking it would be kind of pointless.
Flashcookie and localstorage based techniques are hardly legal. Store user profiles server side, but you will still be fooled by a different visitor id in the cookie (and fingerprint for that matter), won't you?
ETag cookies work quite well too and don't require any additional software or "hacking"-esque approaches.
[1] http://www.zdnet.com/blog/btl/ad-network-at-center-of-third-...
EDIT: probably sarcasm, but still will leave this here