Ditto, checkies should never ask a question unless they know the answer and can produce it without resorting to notes. Otherwise, candidates will not respect them.
Yes and no.
I learnt a great deal from some outstanding
trainers who had the incredible skill of holding a conversation that expanded my knowledge, offered practical advice and generally added to my confidence by not highlighting my lack of knowledge but allowing me to show what I could add to the discussion.
As a trainer myself, I always tried to use the same "discuss rather than question" technique and this would often produce situations where neither myself nor the trainee knew the answer to an aspect of the conversation. This would lead to me asking a question that neither of us knew the answer to and the trainee knew it. "Buggered if I know but I reckon I know where to find it" was often the response from me! It also levelled the gradient (yeah weasel words I know) between us both and also encouraged the trainee to question themselves (and me) without feeling they were demonstrating their lack of knowledge and jeopardising a successful outcome to their training.
......And any trainer that doesn't believe he can learn from a trainee is missing a significant opportunity to expand their knowledge.