Doc Searls:

If brands still want to do “interest-based” or “interactive” advertising (adtech’s euphemisms for what it actually does) they should realize five things:
 Adtech sucks at branding. Hundreds of $billions have been spent on adtech so far, and not one brand known to the world has come out of it.
 Yes, it works, about .0x% of the time, on average. The other 99.9x% of the time it produces nothing but negative externalities, including lots of tendentious math by agencies and platforms to justify the expense. Among those externalities are subtracted value from brands themselves.
 Yes, direct response marketing does work, and it works best when target customers have already opted in, consciously and deliberately. (Note that there is a great deal of ambiguity about how much being a Google or Facebook member amounts to deliberate and conscious agreement to being followed and targeted, privacy controls withstanding. The choices in those controls should be much more binary and clear than they are.) So if L’Oreal wants to get a conversation going with customers of Lancôme, Giorgio Armani or The Body Shop, they should do it by those customers’ grace, not because the robots they’ve hired guess those customers might be interested, based on surveillance-gathered personal data.