I think you can see drive in a candidate's eyes, and in a candidate's background. For the background part, I like to see what someone has done. Not been involved in, or been part of, or watched happen, or was hanging around when it happened. I look for something you've done, either in a job or (often better yet) outside of a job. The business you started and ran in high school. The nonprofit you started and ran in college. If you're a programmer: the open source project to which you've made major contributions. Something. I also like specifically looking for someone who comes from some kind of challenging background -- a difficult family situation, say, or someone who had to work his/her way through school -- who is nevertheless on par with his/her more fortunate peers in skills and knowledge.
Curiosity is a proxy for, do you love what you do? Anyone who loves what they do is inherently intensely curious about their field, their profession, their craft. They read about it, study it, talk to other people about it... immerse themselves in it, continuously. And work like hell to stay current in it. Not because they have to. But because they love to.
Ethics are hard to test for. But watch for any whiff of less than stellar ethics in any candidate's background or references. And avoid, avoid, avoid. Pick a topic you know intimately and ask the candidate increasingly esoteric questions until they don't know the answer. They'll either say they don't know, or they'll try to bullshit you. Guess what. If they bullshit you during the hiring process, they'll bullshit you once they're onboard. A candidate who is confident in his own capabilities and ethical -- the kind you want -- will say "I don't know" because they know that the rest of the interview will demonstrate their knowledge, and they know that you won't react well to being bullshitted -- because they wouldn't react well either.
Arun Natarajan is the Founder & CEO of Venture Intelligence, the leading provider of information and networking services to the Private Equity and Venture Capital ecosystem in India. View sample issues of Venture Intelligence India newsletters and reports.