I would bet targeted advertising works best for certain classes of things, but I rarely actually see targeted ads for them. Like, fashion and clothing can be p

I would bet targeted advertising works best for certain classes of things, but I rarely actually see targeted ads for them. Like, fashion and clothing can be pretty individualistic so it might actually help to micro-target. Not even just for styles, but if you're a swim suit maker who specializes in plus-sized clothes you can target ads at them. You could even not bother sending ads for a sale on jeans to people with, say, size 30 inseams if you're sold out of jeans in that size. I never see them used this way though. But almost every use case I can think of that is mutually beneficial (like the sizing), seems to be demographic information rather than behavioral analytics. I'm having trouble coming up with a way to leverage behavioral analytics in a way that doesn't seem invasive or impertinent. I guess it might work for content curation/recommendation engines (movies, books, music, etc.) But even then, you just need to know people's backlogs and basic demographics, you don't need to start snooping on their web browsing behavior.