Are you really certain about that? The fakes are so good sometimes I don't notice for a year or two. There are so many ways of faking different products, and the fakers are getting really really really good at making the product seem real.
Have you done a few hours of searching and testing for everything you've bought? This is what it takes, IMO, to feel some level of confidence in an Amazon (US) product being 'real'. The levels of suspicion never really go away either - since I've been duped by probably a dozen products at least, that have turned out to be fake, I'm highly suspicious of any Amazon purchase.
It's been a couple years since I bought anything from there. Too much stress worrying about authenticity to make it worth it.