It's poorly done retargeting, but a common mistake. Advertisers create a cookie list based on people who visited a particular product page. They fail to subtr

It's poorly done retargeting, but a common mistake. Advertisers create a cookie list based on people who visited a particular product page. They fail to subtract from that the users who visited the checkout page. If you're paying on a CPC, the cost to you (the advertiser) is negligible. Most people who have already purchased aren't going to click your ad again. If you're paying on a CPM or CPV basis, then you're liking wasting money. It probably gets lost in the noise of the waste in all advertising. I have no idea if it's negligible or not, but it would help the user experience if the larger players helped more.