It isn't just a question of "it's a fake Armani, but who can tell?" - when it comes to genuine Bluetooth, the fakes may not work properly. Several designs have been found on store shelves which had a maximum range of only a couple of feet.

A serious campaign is starting to make retailers aware of the fact that if they want to, they can check to see if a Bluetooth supplier is a member, or whether the product they're being offered at cut price is a probable fake.

And if it's a fake, they risk losing all their stock in a Trading Standards raid.