I try reasonably hard to only by ships from and sold by amazon, but even I occasionally mess up and end up getting a 3rd party seller. Fortunately I've not been burned, yet.
The problem with "ships from and sold by" is that it doesn't address one of Amazon's other big problems, counterfeit items commingled in their inventory. Have a shipping container full of good quality counterfeit XYZ? Ship it to Amazon to sell, it'll get mixed in with the same UPC from everyone else including Amazon itself and the counterfeits will never be traced back to you.
One would think Amazon could trace it back if they tried hard enough, but we can't assume they would do that. After all their margins on commingled items are probably better than when they buy the items themselves.