If you're doing this from a chrome browser that you're logged into, then it's the advertiser that is at fault. Clearly, if you bought the item, then they should

If you're doing this from a chrome browser that you're logged into, then it's the advertiser that is at fault. Clearly, if you bought the item, then they should now have you in their system as a conversion. With that information and you not clearing your cookies, they should have setup their campaign to not target you for the same item. It sounds like lazy advertisers. To answer your initial question, it works and it works really well. As advertisers, we see a significant difference in sales when we don't advertise online. This is especially true for search advertising and retargeting. ToFu first touch display advertising doesn't necessarily work as a sale generator. It's the subsequent advertising / display retargeting we do afterwards that works. Unfortunately for advertisers, the days of doing the way we do things will come to an end with third party cookies essentially going away. It'll be interesting to see how digital advertising changes (specifically for open garden platforms like Google ads) without the third-party cookies.