I bought a monitor once on amazon a couple of years ago. It seemed legit -- packaging looked authentic. Monitor looked authentic. But the power cable was really weird and clunky. It had no branding on it, and everything was written in Chinese. It barely fit into the monitor, and the monitor would only turn on if the cable was in exactly the right position. This was an LG monitor, and not a cheap one, so I contacted amazon and they accepted the return and sent a replacement. Well, the replacement was even worse. Same thing where the power cable seemed incredibly cheap, but the monitor itself seemed fine, but I couldn't even get it to turn on unless I was actively holding the power cable into the monitor.
Ended up just returning it again, but thought it was a fluke. I still used amazon for a while, but this type of thing has become so common that I don't use them anymore at all.