You don't because there is a very very competitive market for counterfeits of these products. For some shoes there might be five or six counterfeiters competing so they may distinguish themselves with higher quality and uphold a reputation that way.

Then there is a whole community of people that evaluate which batches are of higher or lower quality. Personally I don't buy counterfeits at all, the hyped shoes nowadays are just reskins of old designs and aren't that comfortable or imo look that exceptional.

Certainly, don't buy counterfeits that plug into mains though, unless you really really really know what you're doing.