Look for Passion.

"Nothing great in the world has ever been accomplished without passion." ~ Georg Wilhelm Friedrich Hegel.

There was a time when you could size up the character of a man by just looking at the heels of his shoes, those days are long gone. There was a time when you could simply ask "Who do you admire and who do you respect" and the answer would fly off the tip of their tongue without a thought. Those days are long gone. So how do you quickly determine the fillies from the flakes today? ~ You look for passion.

"Tell me what you are passionate about". Tell me what you love - what you hate. Talk to me about the people that you love being around and the things you love doing." Tell me what inspires and motivates you.

Then listen very carefully. Can this person immediately dive into a passionate discourse or do they have to sit back, ponder and think?
If they have to sit back, ponder and think - If they don't immediately know what they love - If there is no passion ~ kick them the hell out.