Interview Necessity - Confidence!

I recently held an interview with a potential employee. He submitted a resume on regular copy paper, he came to the interview in street clothes, and he wasn't very articulate. But I couldn't deny the experience he posted on his short resume, the resume was printed and organized well, and as he spoke, his candor and obvious knowledge of the job was inspiring and intriguing. I felt as though this candidate's confidence really overwhelmed any lack of presentaion of his resume and appearance. It really made me think - confidence in yourself really outshines most negative aspects of an interview... What do you think is the most important attribute of a candidate?