Easiest way to earn your team's trust and support as PM is to develop intimate customer & market understanding. Having a well developed spidery sense is not only a huge plus but an requirement. On various occasions you have prove that you know and care about customer more then anyone in the organisation. This can be tricky thing to accomplish as many PM rely on others for market & customer information. In other cases PM job description may fail to communicate your responsibility as customer evangelist clearly. Keeping all this in mind ability to filter noise from signal and developing strong intuition about market becomes the most critical skill for PM's survival.

Now coming back to interviewing questions I think any question that help you gauge a candidate on above skill parameters is a good question.

Moreover I believe organisations as well as products go through an evolutionary life cycle and each stage requires different attitude and temperament from new PM. It would be better if you keep your organisation and product goals transparent in the interviewing process. Let the candidate evaluate product path and if it'd not fit into your organisation goals communicate your desired product trajectory to him so that he can answer your question according to new expectations.