People say it's a big problem but to date, having bought in the low five digits of audio and video hardware mostly from Amazon, I've had zero (obvious) counterfeits and very little defective gear generally, all of which was manufacturer sourced.

I'm sure that counterfeiting is a real problem, but I don't know how pervasive it actually is.

I have bought thousands of dollars worth of electronics and stuff from Amazon. Zero counterfeits so far.