Let's be frank. Most interviewers aren't very good at interviewing. Here's why.
One quarter will overvalue the first impression you make.
If they like you, they'll ask easy questions to justify their instant reaction. If they don't like you, they'll ask harder questions to justify their instant reaction. None of this has anything to do with your ability or motivation to do the actual work required or how you would fit in with the culture.
One quarter will overvalue their intuition and judge you on your assertiveness and how articulate you are.
They'll figure this out in 10 minutes. These people will then boast they can assess anyone in 10 minutes but ignore the fact that more than 75 percent of the people they hire aren't as good as they expected. Worse, more than 75 percent of those they didn't hire were far better.
One quarter will overvalue your technical brilliance in comparison to theirs.
These people will ask you to solve problems that have nothing to do with the actual job as a test of their ego, will, and intelligence. Despite the fact they have a good track record of hiring smart people, they have a terrible record of hiring people who make their commitments, get projects done on time, work well with others, prioritize well, and are effective communicators.
One quarter will assess your ability and motivation to do the work required and fit within the organization.
These people will clearly describe the work that needs to be done and ask you to describe comparable accomplishments. They'll likely describe a realistic problem and discuss how you'd address it. These people have a track record of hiring great people.
Those who overvalue first impressions are easy to spot. One clue on the positive side is when they start selling you on the job even before they know anything about you. A negative clue is that they look bored, ignore you, constantly look at their watch, or ask you tough questions that are so narrow in scope it's impossible to answer correctly. Regardless, when you're in either situation, ask the interviewer something like, "Would you mind giving me a quick overview of some of the biggest challenges in the job? I'd like to provide you some examples of work I've done that's most related."
The intuitives are also easy to spot. They'll be neutral at first, but if they sense you're smart via your vocal skills and confidence they'll relax a bit. At this point they'll begin a more open dialogue but they'll be more general about process, strategy, tactics, or planning. If you're a bit nervous or don't fit their stereotype they'll rush to end the interview. If you sense the conversation going astray, you need to take instant control. Start by saying something like, "I understood that the person in this role would be handling [here, describe a big challenge you know is part of the open job]. This is something I managed when I was the [title[ at [company]." Now don't wait for permission to describe what you did--just describe it for a minute or two, including details about the results achieved. Then ask, "Is this consistent with what you need done?"
The techies are even easier to spot. They'll start box checking your skills and ask you to solve some tough problems. Some problems will be job-related but others will be outlandish or meaningless. Whether you answer these questions appropriately or not, it's important to proactively intervene to better understand real job needs. One way is to ask, "How is this skill actually used on the job? Once I know this I can provide some examples of how I've used the skill to solve job-related problems. Based on this, we'll both know if I'm a fit for the job and interested in doing it."
Good interviewers are a little more difficult to spot since you'll be surprised that their questions are meaningful, they have a clear understanding of real job needs, they ask lots of related fact-finding questions to determine if you're competent and motivated to do the work, and, most important of all, they are truly interested in what you've done. When confronted with this type of interviewer, just say, "Thank you."
Most interviewers ask questions unrelated to real job requirements. As the person being interviewed, you need to take control to ensure you're being evaluated properly. This starts by asking the person to describe the job in terms of real objectives and challenges. Then you need to describe work you've done that's most related. You'll know you've been successful when the interviewer asks you if you're interested in the job and if you'd like to come back for another round of interviews. But be careful how you answer this one -- it might be a trap.