[PaulHoule]

Depends what it is. I would trust Nike products from Dick's Sporting Goods physical store and from the Nike store online but not Amazon or any other online retailer. I'd be suspicious of perfume from (say) Giorgi Armani because rip-off artists have heard of it but who would rip off an boutique bland like Phlur?

[mrWiz]

It probably goes deeper than you expect. A friend of mine unknowingly bought counterfeit Darn Tough socks from Amazon, and only found out when he sent them in for warranty repair. Clough42 has a video on YouTube about identifying counterfeit Mitutoyo calipers (though I believe they came from Ebay rather than Amazon).

[PaulHoule]

Well back in the 1980s my mom was a clerk at a Jordan Marsh story that turned into Macy's selling men's clothing.

She would rail against fakes and would show you how the seams and other details were different and how, looking close, the difference was obvious.

My Uncle Dick, the oldest of the brothers, bought three fake Rolexes from the back of a truck on a trip to see my Great Aunt Simone in NYC. He thought he got a steal. Two months later he reported that they didn't run anymore!