In the cases you provide, though, it seems to me (and I am certainly no expert) that you wouldn't need to advertise the same item again. If I bought a vacuum that I'm unhappy with, showing me another ad for it (which is what Amazon does) is the wrong thing to do. Not only will I not buy the same machine again, but I will google and research the products- I will ignore ads unless they are offering me a discount on the one I decide on. Likewise for wrong-sized jeans or buying three more pair.