It isn't good for consumers whose privacy is being violated as they are being annoyed with unwanted, irrelevant ads and they get charged higher prices due to the cost of the advertising.
It isn't good for companies buying the ads by participating in sham "auctions" with no real insight into or control over the process. They are literally begging to be ripped off.
It doesn't have to be this way. "Context sensitive" advertising is more privacy respecting, easier to implement and monitor and can be more cost effective.
Example: The fact that I recently shopped for and bought a car is no reason to show me auto ads on a web site devoted to pet supplies. There is a logical disconnect here because context is ignored in favor of "personalization".
Those paying for these dumb "personalized" ads are wasting their money and my time and bandwidth because I already made a purchase. I'm not making another one any time soon.
By the way, this doesn't really happen to me any more because I now block these "personalized" ad networks. And you should too --- it's the only logical recourse to this stupidity.