In interviewing hundreds of people, I’ve found that the way a candidate answers one key question tells me more about them than any other. I'll usually wait until the candidate has relaxed somewhat and begins to open up. Then, about halfway through the interview, I'll ask, "What has been a moment of significant professional disappointment or failure, and what caused it?"
Straightforward enough, right? Yes, but I'm listening for a few key things. First, it asks an interviewee to come up with a specific moment. Rather than the standard "What are your weaknesses?" question, which more often provokes groans from jobseekers, it asks for a concrete professional incident. But this gives a candidate plenty of options: Do they focus on a lost promotion, or a failed project? Do they make it about themselves, or about their company? You can see a lot of their personality by how they interpret the question.
What's more, by asking what caused the failure, the question doesn't require an applicant to take responsibility for it, though they might choose to. In my experience, these are three types of answers I typically hear—with some responses earning better marks than others.