This is true, however I am not sure the ‘stupid act’ is just because people would judge them. Just as much of it is that it is so damned tiring to be looked at as if you’re talking Klingon (when you’re 99% sure it was just plain English) and having to explain what you just said 3 times just to have someone nod, and know they are just being polite but still have no clue what you were talking about. Opening up is something you do when you know it’s worth the effort. For the rest you either play dumb or identify the one area the other person does have some interest/knowledge in and stick to that topic.