I suspect that some people will get really heated up about this and argue with me, because they are trained hairstylists or salon owners or whatever, and I admit to not being an expert. Most of the explanations, however, of how fake, expired, or stolen salon products supposedly end up in mainstream drug and groceries stores have all the earmarks of a conspiracy theory. Namely, they don't stand up to scrutiny or make a lot of sense, when you think about them. In some versions, the shady distributers are storing up products for months or years until they expire, because then they apparently can no longer be tracked by their bar codes after a certain amount of time (?), and then they sell them to CVS, Target, etc. And that major corporation is totally cool with this, because they don't fear lawsuits from selling supposedly contaminated products one bit! Nope! In other versions (and sometimes combined with the previous ones), the crooks are emptying out half of the good product and filling the rest of the bottle with water or alcohol because . . . ??? Do they also have a stockpile of fake bottles to dump the other half of the product into? In that case, why buy the legit product at all? Why not just fake it all?
Anyway, yell at me if you like, but I suspect that this is something that stylists are taught in school, probably by people who really do think it is true (and maybe those people are told it by salon hair care brand sales reps). I don't think the stylists are lying - I think they believe it. Just like when they tell you that drugstore products with silicone will make your hair worse. The most logical explanation is that salons want you to buy products from them (which is reasonable) and so they need to have some kind of explanation for why what you find at the salon is better than what you find elsewhere.
I'm not saying there aren't counterfeit beauty products out there. But I doubt that Walgreens has been selling them - or stolen merchandise - for decades with no repercussions.
Do you have a better explanation for how this "gray market" functions? One that explains how it is profitable to the distributors and worthwhile to the large retailers? I'd love to hear it. ETA: I'm not just saying that. Everything I've found has been unconvincing. The argument that they sometimes actually cost more at mass retailers than salons is interesting, but not totally relevant, I think. That's just about shopping around for good prices.