Well, I think is personality. If you ask me why I'll say you that the other posibilities don't need an interview. Your qualifications or work experience are expressed in a résumé that normally you give, and interviewer can study it previously the appointment. On the other hand, the appearence can help you but you must offer something else. So, your personality will be absolutely essential to decide who interviewee past to the netx prove or obtains the job.
That's my opinion. There are another, but they are'nt mine. (little joke)