I consider this the to be the opposite -- smart people that ask questions straight away when they don't understand something is the opposite of looking stupid,

I consider this the to be the opposite -- smart people that ask questions straight away when they don't understand something is the opposite of looking stupid, and it's the first thing I ask new hires to do. I don't want employees that say "yes" but rather ask "why?", and I most definitely don't want employees to answer questions if they don't know what they mean to begin with just to save their face. There's a difference between not saying anything and asking "What are you referring to right now specifically?", "What does DMA mean in the context of the server?" and "Sorry, I'm very experienced with X. How hard would you say is it to do Y with it compared to doing it with Z, which I have worked with in the past?". Not only does it show that a person is listening, but it also improves the ability of everyone in the team to express and elaborate on details that are relevant to the topic being discussed.