Exactly it's NOT recommend and it's NOT A GAME TO PLAY....I did it once at a Breitling AD, and I find me little stupid to did it. Be veryyyyy careful to never bring a rep in a AD to show them your watch just to tease them, always keep it on your wrist... the seller can be stupid and don't know about super rep, if he ask you to see your watch, and just because he's not sure, and he doubt, and show your watch to his watchsmith in the backstore, and if he open the case, HE WILL KNOW that is a rep. This probability is very thin, but it is there. If you are lucky, they will just kick you out of the store with your watch, and you will never be welcome there again, or, they will just keep the watch, and they will tell you, "we keep the watch, or we call the police, decide". Sure you will leave, but you will loose $300-$400.
Never go to a AD to adjust your bracelet, NEVER. Don't try to be smarter than a AD, just play low profile, this hobby is underground