In my case, I guess 90% of searches either include the term "stack overflow" or "Wikipedia", or get augmented by them when an initial search doesn't give desired results. I can't see how such searches might produce adverts that would help answer my questions.

It's very rare that I search for a product and even then, chances are that I add "review" or "sucks" (can work fine in combination with a specific product; negative reviews often tell you more about a product than positive ones, just like a requirements document or a product road map becomes a lot better if one includes things that people might the product to do that it will not do)