There are a lot of ways your bartenders can steal from you, including undercharging (in the hopes of a bigger tip); Z-ing out register tape early and not reporting all sales; staging a fake walkout; using personal, smaller jiggers and drinking the difference… the list goes on. It's hard to tell which bartenders would steal from you, and which ones are honest, but this question is a good one to weed out thieves. Thieves hate to be confronted, so asking a question up front to show that you are tough on bar theft will scare many dishonest bartenders away.

Of course, there is no one right answer to this question, but if your interviewee has an answer that you agree with, that's a good sign for you.