But when answering a question there are, surely, natural traps an interviewee inevitably has to avoid. And not doing so is a potential black mark the interviewer has to watch out for.
That said your argument is fair - and I'd probably agree. But I di think laying intellectual traps can be appropriate. It really depends on your candidate and the interview: if you go into an interview (either as the interviewer or the interviewee) with any form of fixed agenda then, yes, things are going ot be fake and plastic (90% of the interviews I went to were like that). You adapt to the situation: if you candidate is showing intellect and sharpness you test that and start a sort of push-pull intellectual "battle of wills". If he detects that and doesnt like it he is not the candidate for me - I would hope he detects it, calls us on it and avoids the "traps". THAT is a good candidate, for me at least :)
As an interviewer meeting potential candidates YOU are representing your company. If you're acting false and laying little traps etc. and your candidate detects this, you could lose a very smart and productive person simply because acting falsely is a natural turnoff.
On the other side, if the candidate is answering questions in some sort of rehearsed way it'll be a turnoff for the interviewer.
Good interviews are no different than meeting people. As a candidate, be yourself, don't worry about silly traps. Your goal is to show them who you are and find out who they are to see if there's a fit. If you've already decided you want the job before meeting with their representatives then you're potentially making a bad decision and wasting your own and other people's time. If you're egotistical and feel a need to point out that a question is useless, then by all means do so! That way they know what they're getting and can make an informed decision about whether or not they can deal with that. You may want to work on the ego a bit in general, but not specifically for an interview... that would be fake.
Don't try to con your way into a job because there's a very god chance you'll be unhappy if you get it.
Don't be fake and cagey with candidates because ultimately you could scare away some really excellent employees. Intuition is important as an interviewer so you can detect when someone's being fake with you without being a weirdo yourself. Ask questions you actually want answers to instead of trap / fake questions.
The whole fake / fake thing just perpetuates itself and makes it next to impossible to find good fits. It should just be common sense without all this complicated trap nonsense.