We actually had to make a checklist sheet to cover situations EXACTLY like that. IE- Look the client dead in the eye and explain that the stand is THEIR responsibilty, regardless of who returns it and that the person who does return the stand is the one who gets the deposit- so send someone you trust who's gonna give you your $100!
We've actually had to threaten to call the police and report stands stolen a few times! That was back in the day when we used to just take a credit card number for the stands. People would cancel the card before we could charge it when it didn't get returned. One time, after calling for days on a stand, then trying to charge the card only to find out it was cancelled, we finally drove over there (stand was rented the following week to a bride who's design was dependant on it and it could not be replaced in time). The man who answered the door said his mom had it in her car and she wasn't there blah blah blah. My husband told her "Ok. Well just so you know, we're going to report this stolen today so you might want to let her know."
The guys was like "Hold on." He goes inside for a minute and then comes out with car keys and low and behold, the cake stand is in the trunk of the car right there in the driveway. People are so ghetto.