Edit to add: just last week I ordered a potty training seat from Amazon. Great reviews. Supposedly installs into every kind of toilet. It shows up and, predictably, does not work properly with any of our toilets. I wish I would have gotten it from Target or the local consignment store where I could look at it and ask about how it works, and I probably would have if not for the lock-down. So Amazon is getting my business right now, but it's very begrudgingly.
Upside is it soft-closes, so as to not BANG shut.
There was an article recently with pictures of the real and fake items, both from Amazon. You wouldn't know which was which even if they were side by side.
But the fake will probably fall apart faster, may leak poison and is overall not what you thought to buy.
And that is all aside from the issue of fake reviews, which are so prevalent as to be the nrm. So the product might be an original, but it is not what you thought you were getting in way of reliability or noise et al.
A fake wire sodder, which was pretty expensive and cost me in damage to the item I wanted to build. I turned to the manufacturer and complained, and they asked me to send images... it was a fake.
We got Desitin with a very weird consistency and smell. I am convinced it is not real, and have been afraid to use it.
An external disk drive, wich wasn't fake, but was also clearly not the brand it said on the box. I complained about that, and am still waiting for a resolution.
Those are what I recall offhand, but mostly have been avoiding Amazon.
https://thewirecutter.com/blog/i-bought-these-things-from-am...
Even when it's not counterfeit a lot of brands sell a cheaper version on Amazon than they do through other retailers.
I would really like to wonder of the people encountering frequent fake products on Amazon, what categories are you shopping in? Is it fashion items or something similar? My main Amazon purchases are household items/toiletries and then hobby electronic parts. I haven't had any issues with these - and beyond the review issue the Amazon pricing/delivery time/return policy is by far the best of any site I've dealt with.