If you were to bring a wingman or winglady along for a sale, it would be good practice to have this person take a picture of you and your prospect during the sale for candid reasons i.e. as a momento or Facebook events, etc.
If the prospect is avoiding the camera, your alarm bells should be ringing by now.
If he did pose for the picture and later stole the watch, you'll still have a lead.
Can't be too careful these days.
I hope you'll recover your watches soon.