I was talking to my friend about this the other day. He's an executive at an ad company (not Google). He had an interesting take on this: Yes, it is in fact working and breaks targeting and retargeting. But what is the outcome of that? The CPMs (how much the website makes) are 10x higher for re/targeted ads. So as they stop working, do you think the website will cut their revenue? No, they'll either put up a paywall,…
I don’t get targeted ads. They’re quite dumb. If I look at product X, ads for product X follow me around the web, which isn’t that useful because I’ve already done my research and am not quite ready to hit “buy” no matter how many ads you show. Ads for similar products I might be interested in, but I’ve not seen too many of those served up by these ad networks. Untargeted ads at least might show me something new and…
Retargeting has better results than any other type of targeting but unfortunately there's a gap between the ecommerce systems knowing you bought something and the ad networks used to market those ads. It's easy to drop a pixel and say you looked at a product, but it's much harder to let that same network know that you're no longer interested for whatever reason.
Add in complexities like multiple devices, browsers, ecommerce stores, payment methods, and it only gets harder. This is usually why retargeting is much better with smaller direct-to-consumer companies which tend to have a single customer database and payment method to sync from.