Punishing the outliers
Mushahid points out that a nearby McDonald's has a sauce policy. If you want six or eight packets of dipping sauce for your chicken knuckles (or whatever), they charge you for them. The sign is big and loud and probably in ALL CAPITAL letters.
I can see why this happened.
99 people out of a hundred take one or two packets of sauce. One guy takes 20. This is infuriating. You lost money on this guy. He's a pig. He probably hordes the sauce and uses it on his eggs in the morning or whatever.
Like the jerks who buy a couch at DWR and then return it after the party.
Just because you're in business doesn't mean you have to be a patsy, doesn't mean you have to give away everything all the time. Or does it?
There are two pieces of math that might help you figure this out. The first is simple: How much do the bad guys cost us? If it's a cost of doing business, it's probably not worth changing your atmosphere/guarantee/state of mind over. Sure, shoplifting would go down if you locked up each item behind the glass. But punishing the majority costs you far more than the theft does.
The second is a little more subtle: does the bad behavior spread or damage the experience of the good guys. Not in the sauce example, certainly, but yes when it comes to people spamming your comments board or smoking in the elevator.
If I were McDonald's, I'd just add another item to the menu: Extra sauce, 20 cents. Give your frontline staff the authority to waive the fee for good customers or small extras ("I'm supposed to charge you for the extra sauce, but don't worry about it, it's free for you today.") but it's an easy way to deal with the guy who wants 25 packets. It doesn't offend the good guys and provides a limit for the bad guys.