They don't seem to be able (or willing) to distinguish between items you might want to repeat buy and 'one off's. I was sent a question by Amazon on behalf of a customer about a map I had purchased a few years ago which I answered in some detail. I then get flooded with invitations to buy that map again. How did I answer the questions without having the map in front of me? I now have a disincentive to be helpful.The advertisers are paying to display banners to people who've already bought it, sometimes even bought their own product. Just booked a cruise through MSC, today, there are MSC banners on virtually all fora and other websites I've been using - completely pointless as I won't be buying another. Same the other day, I bought a new DSLR camera from Amazon - for a few days, there were nothing but Amazon camera banner ads. You'd think they'd design cookies that could flag up when an item had been bought so they don't display advs to people who've made the purchase and concentrate advs on those who havn't.
If I had bought the map with cash, no such worries!