for sites that I like, I always unblock ads to support them, though I will block annoying ones regardess of the site.
For example, expect your ads to be blocked if you do some stupid, retarded, ignorant moronic crap like popup ads that act like landmines if you mistakenly touch the wrong word with your mouse.
Or worst having random flash animations or ads that play audio.
Other than that, ad companies need to improve their ads and better vet them.
I will not buy anything from a shady ad. and anyone who has been on the internet longer than a billionth of a nanosecond, will notice that what ends up in your spam folder is the same crap that ends up in banner ads.
With all the tracking they do, you would think they would be able to provide useful ads.
eg, if I am searching for some liquid coolers that are compatible with socket AM3, then
show me ads for liquid cooling systems. I am trying to buy some. Showing me an ad about sneakers or some herbal supplements is not something that I am in the mood for buying, and showing me is only pissing me off and wasting both the servers bandwidth, and my bandwidth, which I assure you, is far more limited than what the server has.