You'll never know exactly why interviewers ask you the questions that they choose, but it's typically not for the reasons you think. Even interviewers who ask the exact same questions may do it for different reasons. Usually, the questions chosen help determine how you are going to react in certain situations.

The most difficult question that someone asked me was this: "You are a Recruiting Manager, which means that it's your job to evaluate candidates. In looking at your background, why would you NOT hire you?" Not only was it a difficult question, it was brilliant. The interviewer was probably asking me this question for three different reasons:

1. He wanted to see how I could react to a stressful question.
2. He wanted to see how I think.
3. He wanted to truly know why he should not hire me and he knew that I would have the best answer because that is what I do for a living.
4. He wanted to ask me what my weaknesses were without asking me outright. He knew that he would get a truthful response, which he did.

I told him that the reason I would consider not hiring me is because my resume appeared to be jumpy. While I did have a job that lasted five years, the past year was less than stellar, at least on paper. I had three different contract assignments all of which lasted a short time. To me as the Recruiting Manager, I saw that as a potential problem. Here were my questions about me as a candidate:

1. Was I a job hopper?
2. Was I someone who would get bored quickly?
3. Was I someone who was let go from three different assignments?
4. Was I someone who needed more variety than this job could offer?
5. Was I someone who was worth taking a chance on?

Somehow I reached way down into the depths of my experience, miraculously figured out how to answer it, and also managed to spin it positively.

I told him that although my resume appeared to be jumpy, I would ask myself about all of the recent experience to determine if it really was. I would recognize that all 3 assignments were temporary and completed before I left. I would ask myself for references to determine whether I was correct about my assumption. I would determine whether the projects that I completed added skills to my repertoire that would benefit the new company. And, last but not least, I would recognize that I had spent five years at a company before this year.

Apparently it worked. I was hired and grew through the ranks of the organization to become Senior Director of Recruiting, seven years later.

source: http://www.absolutelyabby.com/interviews/would-you-hire-yourself.html