I have attended several interviews and also have interviewed several people. I have seen the difference between the people I interviewed with and the way I do interview.
In the interviews I have given for several job positions at companies I don't want to mention here, most of the time I felt that the person who is interviewing me is not at all achieving his goal of the interview. What that person is trying to do is to prove to me that he/she is smarter than me in all respect.
For me interview is a combination of 2 words "inter" and "view". That means exchanging views among people involved in the process. Thus what I expect is to have a debate on the subject in question. But mostly what happens is not a debate.
In one interview, I was given a problem to solve. Instead of listening to my solution and to have a debate on my solution, the Interviewer was playing some game on this iPhone. I was explaning the solution to him and that person was not even listening to me. Instead he was trying to be an smart ass, saying your solution is wrong. My question is how can a solution be wrong if it can solve the problem. The solution may be not efficient enough. Nevertheless solution is never wrong. Other person may have different solution in mind (which may or may not be the efficient one), but still the purpose of the interview is not achieved.
What I like to do when I am conducting an interview is not to prove that I am smarter than the interviewee (which I am :-)). What I am trying to gauge is the knowledge and the potential of the person opposite to me. I am a believer a person willing to learn and push his/her limit can do wonders. No one is born smart. Smartness is achieved by hard work and will to gain more knowledge. I always try to find a person who can fit into my immediate job description and is smart/hard working enough to achieve more in the near future.
At least in the technology field, what I find is that interview is a lost cause. Most people are I interviewed with are trying to prove that they are smarter than me or they are the smartest people in the world. They are not even try to find if I can fit into the current job and can do more in the future.
Another thing I try to achieve in the interview is the personality of the person I am interviewing. No matter how smart one is unless that person has the right attitude and the personality, he/she cannot fit into the team. It takes only one bad apple to disintegrate the whole basket of good apples. It is all about team work.
Without a good team dynamics, it is not possible to achieve the long term goals. I takes ne person with wrong attitude in the a big team to lead the project to failure. What happens is that this person will demotivate others in the team. It is the responsibility of the manager solve this problem and also the responsibility of the team members to raise the issue. Again it is the responsibility of the manager to see the signs and take actions at the early stage.
Having the social skills is equally important as the knowledge of the current field he/she is working in. Social skills refers to personality, how comfortable one can make others, how good of a team player one can be etc. etc.