A quick explanation for those who think blocking adverts is evil:
1) Advertisers are usually only interested in click-through rates, not on impressions.
2) People who click through adverts are not the same people who will install an ad blocker.
3) If people who won't click through ads don't see them, then by extension, those adverts that are being shown are more likley to be being shown to people who WILL click through them.
4) This is GOOD for the advertiser who saves on bandwidth. It is also GOOD for the user who doens't want to see them, who also saves on bandwidth.
5) Sites which survive solely on advertising revenue will still attract plenty of users without a blocker installed. Since they usually get paid by click-through rate, rather than per impression, their revenues will not change.
Personally, what I find evil is the idea that not seeing your advert in the first place makes me evil. If I don't want to buy your crap, I don't need to have a garish flash advert telling me about it. if I decide that I DO want to buy something online, then I will do the research as to what it is I want, and find the cheapest retailer. I understand, however, that many people are easily swayed by advertising, which is why the industry still exists, despite its sole purpose being to sell people things they either do not want, or are inferior to another product, which does not require advertising to sell.