Haha this reminds me of an old Microsoft interview technique I read about a while back (2 years ago?). I don't think they do it anymore because, well, it's a little odd.

Basically the candidate would state something that was pretty obvious at some point in the interview and then the interviewer would say that he was wrong. The idea here was obviously to see whether the candidate had "the balls" to confront someone who basically has more authority here and tell him that he, in fact, was the one who was incorrect. From what I remember the reasoning was that in real life, you're often in a position where you have to convince someone higher up than you that they're incorrect and here is why.

I just tried googling for the story for a few minutes but couldn't find it :(

Personally, I always aim to be polite and I don't understand the reason why people believe that "argumentative" is necessarily a bad trait. Sure, it's bad if you argue for everyone and everything but doesn't this mean that you need to do it in moderation?

I think part of the reason why being argumentative has a negative vibe in the general public is because people don't really argue - they just bring their point of view and try to shove it down your throat until you swallow it and agree or choke on it. The mere thought of considering new suggestions is for many people scary.

Argumentative generally means arguing without and real reason to do so. Obviously, yes, you should stand behind your position, preferably with facts to back you up. But that doesn't mean you have to go out of your way to start an argument, or be rude while doing so.

There's a big difference between a disagreement and an argument.

This is a crucial distinction. Disagreeing with someone is valuable. Being argumentative isn't about accuracy, it's about ego and self-assertion. If the person you're talking to can't be persuaded, the solution is to call on sources (or if they aren't available, as in an interview, table the topic until they are.)