I think that for some people, whether or not ads are actually displayed on a web page, that web site won't make a "sale" anyway.
For instance, taking myself as an example, I don't click on ads much less buy something. I do use a pop-up and ad blocker add-on with Firefox but that's because I don't like all the moving graphics in a web site's margins. I wouldn't have clicked on the ads even if I didn't have the blocker.
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