I don’t know how much success you were hoping for in buying a commodity item from no-name brands like that. That’s always going to be a free for all. If you look for mice from reputable companies the results on Amazon are fine.
I personally know a few people who have gotten counterfeit items, even including consumables like protein powder. I don't have to buy from Amazon so it's just a chance I'm not going to take until such a time I can be convinced it's not a problem. It's not any more difficult or even expensive for me to shop elsewhere so I don't have to be particularly rational or thorough about it (I don't have time for that!).