>Just today I was browsing for new wine glasses. I finally found the product that I wanted and checked out a couple of options on Amazon. The first two reviews for the pair[1] I liked were complaining that they received counterfeit items.
Another example: I need new brush heads for my electric toothbrush. I haven't bought them yet, in part because I can't be sure that the toothbrush manufacturer-branded refills on Amazon are genuine. Going with a generic, compatible refill with good reviews is preferable in this case, aside from the lower price, because presumably no one will counterfeit it.