Inventories are not "commingled" they are completely separate in the warehouses. Just because multiple vendors sell the same product and use the "fulfilled by Amazon" service to fool you doesn't mean Amazon is accidentally sending you an item from the wrong seller.
If you purchase from Amazon and don't check that it's "shipped and sold by Amazon" then you are asking for trouble.
The biggest issue is that Amazon has allowed, because of corporate greed, Amazon to become the new Chinese Ebay. The crap you have to wade through to find trusted sources is ridiculous. Amazon has lost a huge amount of trust because of this.
That said if you take the time to verify who the seller is you WILL get items from that seller and NOT from some other random seller. They are not just tossed into inventory together.
If you purchase from Amazon and don't check that it's "shipped and sold by Amazon" then you are asking for trouble.
The biggest issue is that Amazon has allowed, because of corporate greed, Amazon to become the new Chinese Ebay. The crap you have to wade through to find trusted sources is ridiculous. Amazon has lost a huge amount of trust because of this.
That said if you take the time to verify who the seller is you WILL get items from that seller and NOT from some other random seller. They are not just tossed into inventory together.