As we all know, there are two types of Amazon: "products sold by Amazon" and "products sold by marketplace vendors". Of the latter, if an item shipped from FBA is returned, it will not be returned as new inventory.There is a lot of complaints in the internet that people bought new products on amazon and got ones with signs of being used. I had such situation at least twice.
However, I have no way of knowing about the products that Amazon buys and sells itself, or the Amazon brand.