Common products that are normally sold at a high mark-up at retailers, are usually always counterfeit if bought from amazon. Case in point are the expensive electric tooth brush replacement heads by Oral-B.
You will pay $5-$8 per head from a physical retailer. Yet on amazon, there are tons of them being sold for much less. If you do buy one from amazon, the product will not be the same as from a physical store even though the packaging is identical. Its a cheap counterfeit.
Another time, I bought a hand cranked can opener. It was supposed to be a heavy duty "Made in America" can opener. Yet once I got it, the construction was nothing at all like the product images showed (was held together by cheap pop rivets instead of solid rivets) even though all the brand markings (including a big print "made in America") were there. It broke quickly. Looking on ebay I discovered an identical item only instead of it have a printed "made in America", it said "China"...
I bought some on eBay, advertised as genuine but not. The packaging was near perfect. The only thing that gave them away was the different mouth-feel and two misplaced mold release marks.
Genuine Braun dual-action brushheads have two divits on top of the brushhead. The copies have the two divits on the side.
I sent a note to the seller warning him that some counterfeits might have gotten into his supply. Seller refunded me.
If you get counterfeits from Amazon I am sure the 3rd party seller will refund you.
For a major example of this, Apple sued sellers over knockoff (and potentially hazardous) USB chargers being sold as official Apple chargers. “Shipped and sold by Amazon” and as far as customers can tell, it’s the real thing.
https://www.theverge.com/2016/10/20/13343682/fake-apple-char...
Best Buy’s supply chain doesn’t have this problem.
This is common across all sorts of products. A shoe company (I forget which) stopped selling on Amazon because they couldn’t do anything about being mixed in with all the fakes, and fountain pens bought there (Lamy Safari in particular) have good odds of being Chinese knockoffs of questionable quality.
On the other hand, if you buy something retail, you can A. see it yourself first and B. have a physical store you can return it to.