"Commingling" is such a great euphemism for fraudulent counterfeiting.

I can't count the number of times I've ordered a book from Amazon (1st party, Amazon as the seller) and received an obvious counterfeit, with fuzzy text and a poorly printed cover. On one occasion, the scanning/OCR process had missed most of one chapter, so there were just section headers, page numbers and blank pages.

Unfortunately publishers and manufacturers don't have a lot of leverage with Amazon. If there's pressure coming from somewhere, it must be coming from a regulatory body.