Look at current advertising, it doesn't generally help you find the best product that suits your needs, instead it shouts at you that for a small fee you can learn the simple secret to perfectly white teeth.
In your above example no company could legally say that it is making pervert x-ray vision goggles. So what happens is the company with the best marketing strategy (and probably useless non-xray goggles) devises a campaign which alludes to the non-existent x-ray properties of their useless goggles. Google helps them target it at you and do so JUST as that cute neighbor next door is raking up the leaves in her annoyingly baggy gardening wear and BAM you're buying some junk which doesn't fulfill your need.
No doubt in some cases consumers will be provided with a product which fulfills their needs via googles adverts, but generally they will get worse value for money and I suspect they'll also get worse products.