Do you want the product that is considered the best value, the product that is the most popular? or do you want the product that the retailers are willing to pay the most to get you to buy?
Google (well, I shouldn't pick on google. All brokers of advertising) optimize to push you towards the product that their customers are willing to pay the highest ad rates for.
Of course, In a company concerned with it's long-term reputation, googlers will point out, this is modulated by a knowledge that they need annoy the customer less than any alternative.
My point is that an ad is always going to cause the broker to have a conflict between what the user needs and what the customer is willing to pay for, while an organic search result (unless it competes with an ad, which it often does) does not cause that conflict for the ad broker.