I've worked in and around marketing/advertising for the last 6 years in different capacities and have found that the emphasis on audience hyper-segmentation and retargeting to the exclusion of other methods is the single biggest piece of bullshit out there. Targeting people based on what they are apparently interested in vs. places they go that reflect those interests doesn't give better results and can turn off your customers. It sounds cool to marketing teams and it works to get you contest entries, but it doesn't usually translate to more conversions than a well managed campaign would give.
If I buy a mattress, advertising more mattresses to me doesn't make me more likely to buy them; I bought the thing already. Advertising mattresses to a person on a mattress review website, though - that works. Of course, that's harder to do.
Still getting TONS of car advertising, after I bought one 8 months ago (when I see it).
seriously car ads are what pushed me to JavaScript off by default since their ads are almost as rude as porn ads. Even the normal advertising reset trick of "open all in new tab" on a folder with a dozen cloud/server hosts didn't swap out advertising to their normally sane ads.
i bought my friends kid a backpack that looked like an owl. i got advertisements for the it for a few weeks after, which was strange to me. I bought the backpack on amazon, and the advertisements were amazon. didn't they know I bought it already? didn't they know I probably didn't need 2 of them?
"If I buy a mattress, advertising more mattresses to me doesn't make me more likely to buy them; I bought the thing already."
Actually, it is possible that you might want to buy a mattress again. Consider that you found the new mattress to be more/less firm and are looking to return it and get a different one. I think it is reasonable to show ads for the same thing at least till the end of return window.
You may get extreme edge cases, but you're going to pay more to get them because the conversion rate will be low. You'd get more out of targeting placements directly because you would hit all people looking for a new mattress there, not just people that have already purchased one.
If I buy a mattress, advertising more mattresses to me doesn't make me more likely to buy them; I bought the thing already. Advertising mattresses to a person on a mattress review website, though - that works. Of course, that's harder to do.