First, you only ask one of these silly questions during the interview. And it should be one that makes the candidate sweat and think out loud a lot, but one where they'll eventually be successful -- I like the one where you ask the candidate to think of as many uses as possible for X and you just keep going until they run out of ideas.
As soon as this question is over, the candidate is relieved. This is when you take the opportunity to ask them the key question of the interview, whatever that may be, while they're at their most unguarded.
So watch out for these questions: sometimes the interviewer is just trying to soften you up for the next question.
The same thing happened to me in a GOOG interview. Reading your comment, it just came as a picture in front of my eyes! I succeeded in the first question and gave some brilliant answers until we decided that we spent enough time on that part(aka, i ran out of ideas). I was relieved and we moved on to the next question. I didn't nail that one...no wonder i didn't make it to the next round!
I once had an interviewer suddenly ask me if I liked beer. My first reaction was to quickly guess what kind of answer he was looking for. Obviously, his goal was that to see if I was being honest or just trying to give the right answers. Anyways, I told him I liked beer :)
I understand where you are coming from and I just hate this fake hiring "voodoo" of trying to predict the future of a candidate by asking oh-so-elaborate questions and relying on oh-so-psychologically-awesome tricks.
First, you only ask one of these silly questions during the interview. And it should be one that makes the candidate sweat and think out loud a lot, but one where they'll eventually be successful -- I like the one where you ask the candidate to think of as many uses as possible for X and you just keep going until they run out of ideas.
As soon as this question is over, the candidate is relieved. This is when you take the opportunity to ask them the key question of the interview, whatever that may be, while they're at their most unguarded.
So watch out for these questions: sometimes the interviewer is just trying to soften you up for the next question.