Interviewing Realtors
I don't have enough experience, but three things come to mind.
1. How they just are.. their personality, etc. If they annoy me too easily, that won't be good.
2. How well they communicate, how quickly they communicate.
3. Examples of properties they've sold, how they photograph things (or hire someone), what they spend energy on. You learn how keen of an eye they have.
I guess if you're buying, you are more interested in how they will help narrow down choices, how well they know the market, schools, etc.