Things sold on the "grey market" are not necessarily counterfeit perfumes. Most manufacturers of fragrances vigorously fight the distribution of counterfeit perfumes because they are so damaging to the brand they depend on. It is pretty easy to stop the distribution and or the importing of fakes into the U.S. market. and the original companies do so.
Grey Market as normally used here on BNotes usually refers to the distributors and retailers who buy inventory from other sellers or distributors at a deep discount off of wholesale price and pass along the savings to the consumer in the form of a lower retail price. This happens all the time and some retailers specialize in purchasing discounted inventory. This process is the good side of the "grey market" because this market benefits the customer with lower prices and benefits the authorized dealers by being a source to unload inventory and convert it to money. Whenever you hear of a retailer or distributor who is going out of business it is almost always due to slow moving inventory and inventory mistakes that is tying up their capital, rather than lack of profit margin. Grey market sellers help keep the inventory moving and it is a service.
How does normally good inventory end up in the hands of these discounters? When inventory is sitting on shelves and not moving (selling at normal mfg. recommended prices) then often retailers decide to cut their losses and sell inventory to "discounter" or grey market vendor who will move it fast at a lower price to consumers. If a wholesale distributor of a brand, changes to a new brand, or a retailer is closing retail locations, or a large customer decides to stop selling a brand and change up their product mix, they will convert their dead inventory to cash by unloading all of it in bulk to "grey market" outlets. These bottom feeders serve a useful purpose of inventory clean up and freeing up the shelves for new and more interesting products to come along for the normal full price market.