From the inside, you can see who was going to be there for the signing. The first time I saw the sign on the way in, I forgot to look on the way out but wondered for days what was going on here.
Many times a day employees would be going through these doors, at a minimum, the guys collecting the carts. But I have to guess:
(1) There's no sense of pride of ownership.
(2) There's no easy way to point out a problem.
Are you instilling a sense of pride of ownership in your staff?
And have you made it easy to escalate issues for investigation?