I will go straight to the point. I understood the whole concept of when to answer and when not to answer.
I think if one member is answering all the questions, then when he/she goes offline, the community can feel inactive. New members may not get answers, and over time they can get frustrated.
For me, the hardest part is when I am genuinely trying to help someone by answering their question, but they start taunting me and asking, "Are you a mod or admin?" or "Why are you pretending to be one?" As someone who is just trying to help or guide new members, that is the hardest part for me.
If I were a CM, one type of question I would usually answer is when I see someone genuinely helping others but getting mocked or discouraged for doing so.