Let's assume that you're talking to someone and detect red flags. Here are tips to help you tease out the truth:

1. Ask questions that demand more than yes or no answers. If you ask a potential hire, "Did you ever have any problems with a previous employer?" it's too easy to deny with a flat "no." Rather, try, "No job is perfect. What kinds of issues have you had with previous employers?" The truthful person probably won't need time to process the answer, and it'll almost inevitably elicit a more revealing response.

2. Keep most questions short. The person you're speaking with is thinking many times faster than you're talking (that's how our brains work), so don't allow him or her much time to concoct a misleading response.

3. At the moment you notice more than one red flag, probe further. Say, "Tell me more" or "What else?" or "Why do you say that?"

4. Stay cool. The nonconfrontational approach works best — even when, the authors insist, they've interrogated alleged terrorists. "You don't ever want to be accusatory," says Houston, but rather always aim for "low-key and matter-of-fact."

5. End with a catch-all question, such as "What haven't I asked you that you think I should know about?" You never know what new information you'll discover.

Also of interest: Outsmarting the scam artist.