Once a while ago I googled for a bit around the time I was buying a car. For weeks afterwards I got hounded by car ads for some brand. Needless to say that brand is not on my short list for any future purchases.
Any advantage in advertising has turned out to be short lived. It's like building up a resistance to certain chemicals, at some point you need a harder variety to reach your goal. And then the resistance increases and so on. Retargeting will work for a while and then we'll be back to square one, more obnoxious ads and less content. Until all you see is ads.