I'm not sure but aren't most sites paid for ads that people click on? So even if you let them load but don't click on them you still aren't making the site any money right?
(again not being sarcastic or anything... thats just the way I thought it worked.)
Aren't some pay-per-view and others pay-per-click? (I don't run a commercial site myself) Maybe some advertisers pay only per click, but I think some pay a smaller amount per view and a larger amount per click.
Anyway if you leave non-offensive ads unblocked and click on those that interest you, that's more support for sites than if you block all ads.