I am not the OP but the answer to question is very close to my heart.
The pinnacle of non-intrusive online ads have been the original Google search ads. They were out of the way, clearly marked as ads - and hence could be visually filtered out. They were pure text, so could be neatly included as elements on the rendered page. And they were always targeting an INTEREST. Not an individual.
So I would take that as the minimum acceptable advertising behaviour. Not implying that it's perfect, but it's a clear set of ground rules. With that in mind, _my_ ideal, non-intrusive ads mechanism builds on the following rules:
* Ads must never be inline to page content
* Even when clearly out of the way, ads must not be allowed to mimic page content; they must be clearly marked as ads
* Text only.
* I might accept an image within the ad, provided it was always served from the content provider's system.
* As an extension to previous point: if the served image size would exceed a notable fraction of the page size, it must not be included in the output.
* No user tracking of any kind.
* No third-party javascript. Ever.
* At most 15% of display real estate allowed to be used by ads. Including the padding in the UI. (Counts as space denied from content.)
* Not allowed to affect page content load times. Ad material must be included at the end of the page code. If your service pushes ads from internal and separate system, hard timeouts must be imposed: if the internal system cannot serve an ad within an allotted time, the frontend must never be forced to wait. You just missed an ad impression. Tough.
* If clicking an ad takes a user through a bounce page, all identifiable information from the user must be stripped. Bounce page or redirect must not impose any further page loading delay.
* No beacons
Breaking even one of the rules automatically disqualifies you.
If you, as an advertiser, find these rules unacceptable - well, then we are in mutual disagreement. I find your ads equally unacceptable and treat them as a form of cancer.
However, as a genuine service to the user... please allow the user to search for ads that have been displayed to them. Preferably by display context. I would be glad to return to a subject at a later date and search for something I remember seeing earlier.
The above is still not ideal, but everything that behaved according to it would at least be palatable.