What are you hiring for? As a technical person here are some questions that really annoy me (
and why):
-Are you creative/artistic? (
Really? You are hiring me to be smart and solve problems, not design.)
-Are you in this for the long haul. (
This question will always be answered yes but in reality is no, just as you will dump the employee when he becomes unprofitable he will dump you when he finds something better. The idea of corporate loyalty is decades gone and anyone who hangs on to it is an idiot and shouldn't be hired unless they are doing monkey work.)
-We have other candidates, why should I hire you? (
Even if there is a good reason that question doesn't open up an answer because he has no idea what he is being compared to)
-Describe your dream job. (
This is another butt kissing question. No job can ever be a dream job so all the candidate can do is cold read you and describe as best he can you as a manager and the workplace around him.)
While this comic is trying to be funny all the points are completely true:
http://theoatmeal.com/comics/interview_questions
As for questions that you should ask:
-Ask a questions that test their practical knowledge opposed to their theoretical. For instance if you are hiring an electrical engineer ask him for the total capacitance of this circuit
The correct answer is 20 Farad, not 5 which is how you would add a different configuration of those two. That appears to be the purpose of the question but even answering 5 is forgivable. A normal capacitor is a few millionths (or even billionths) of a Farad and a big one may be a few thousands but those are quite rare. Even a first year EE student should know that. If he doesn't ask what sort of circuit would have capacitors that big he doesn't have a practical knowledge of electrical engineering and probably shouldn't be hired.
-If you are interviewing an engineer ask him what is one of the more interesting problems he has solved. This gives you a chance to see his problem solving skills and he will usually love to answer such a question.
-As you probably know, you are not the only person going for this position. So far we have a guy who has [insert qualifications here], why should we hire you over him. (
This gives him a chance to defend his qualifications, only ask this if that guy is real and would be getting the job over this guy)
Just remember that interviews are just as much about the worker choosing you as you choosing the worker. Asking difficult (but not stupid) questions may chase away some but better workers will like you.