The assumption is that the retailers always know that what they're selling is real
How to solve fakes at the distributor level? Maybe you can't, if the companies themselves are in on it. Are there any accusations of that happening?
I haven't bought a box in awhile. I go for a Bolivar Royal Corona when I do, which I don't think are very attractive to fake en masse. But, last time I did, I seem to remember something about a bar code on the box that could be cross referenced to the factory. The box came with several seals, holograms, etc. (fancy arm waving stuff) that looked legit.
I've been smoking that brand for decades now, and I can't say I've ever had one that I thought felt off for any reason. If I were into Cohibas... well, then that would maybe make me a little more nervous. I think Bolivar blows them right out of the water though. Much stronger flavour and rich experience for my tastes... but that's very personal.
Anyway, interesting to know how they might fake them at the distribution level and I wonder if the brands themselves have been involved somehow.