As an interviewer, I would say that this question is a dumb question. Maybe I will ask this sort of stupid question because human resources put me in a situation that I should see those job seekers or I don't like that candidate.
If I am the candidate, I would say "This is not a productive question to be answered because you are the one who spend this valuable time to figure out whether I am the right person. If you really think you are wasting time interviewing me, you shouldn't be here or I shouldn't be invited in the first place. Of course I come here is to get the work done as you are. Therefore, the reason you shall hire me is I am the one will get the job done in logical way and on time."
Do remember don't lie about yourself. It is very easy for a trained interviewer to figure out that you are lying. Don't not make an assumption for the interviewer (e.g. I am the right person for this job) because smart people hates smart people.
If I really like the candidate, I would rather ask him/her the related material instead of those unprofessional question. The aim of the conversation is to figure out the candidate's personality and ability (or even you can find out how honest he/she is) in such a half an hour session.
Interviewer should remember! Unless you are hiring a person to be representing the company in front of the public or just a salesperson, the one who performs the best speech won't be a good employee.
