Most reps are so damn good no one is ever going to be tell. and as my sig says no one really cares. In 20 years no one has ever asked about a watch I was wearing. So why do people worry about a serial number in the INSIDE of a lug? Simple.Because their intention is to try and fool somebody, somewhere somehow.Sometimes for insideous reasons, sometimes because they are posers. They're the ones you see standing next to someone checking the time when there's a clock on the wall.
Ultimately It's rarely because they just love he look of watch X. If so they'd buy an Invicta rather than deal with the issues associated with Chinese reps.
Of course few will ever have the balls to admit is this.