On a related topic: what do people think about ad blocking technology from an ethical viewpoint? For me, I think I use the same screwy morality that I use when I'm downloading music...I don't mind stealing from wildly successful artists/businesses, but I'll gladly pay full price for a CD or click on an ad for someone who's just trying to pay the bills.
I don't do it, as I occasionally find ads relevant and useful - maybe once a month at most. On the other hand, I avoid sites where there are lots of intrusive ads. The harder it is for me to read the content I came to read, the less likely I am to return. In fact, I wish I had a bookmarklet to produce a form message saying 'the ads on your page at [URL] are so obnoxious that I have auto-blocked myself from your site…
Constructive feedback is always good. "Your ad in location XY is loading very slowly." "The ad for product Z is misbehaving and causing a redirect/hang/whatever." As long as it isn't annoying comments like "I don't like ads, you should remove them" or "It moves. Can't you just use ads that I don't notice?" Those are pointless, because they hinge on the concept that ads are fine as long as nobody sees them, which goes against the whole point of ads.