How many consumers have this style of interaction:

* buy an item from Amazon (coffee maker or otherwise)

* realize the build quality/size is rubbish (which from some of the less well known sellers, it really can be)

* return the item using Amazon's generous returns policies (never had one rejected, I've used it many times)

* buy a different item in the same category.

* repeat?

If this type of purchase happens a non-negligible number of times, could that be the reason we see so many 'buy more of X!' style ads?