Wrong mindset. Click-throughs or direct conversions to sale are very bad measures. Nice if it happens, but it shouldn't be the purpose of an ad. How often do you think newspaper ads get clicked on? I think they more often get a coffee mug put on top of them. Yet considering so many ads are bought in news papers, they do seem to be worth the cost.
Same for web ads. It's the impressions that count. It's that people get to see your logo, get to see your product, so that later when they're in the shop they go for the brand that they've seen many ads of, the brand that they know, over some no-name brand. That no-one clicks on them is totally irrelevant.
The only exception is Google's ads - I'm seeing those ads as glorified commercial search results. If I want to buy a product, the ads are what I'm looking at, as that's often companies that are indeed selling the product I'm looking for. If I want general information about that product, I ignore the ads but go for the organic results instead, which tend to be more review sites and the like, which do not sell the product I'm looking for.