Unambiguity about right or wrong is necessary here. It exists when finding bugs, but not in more subtle things. For example, asking a junior for feedback as a

Unambiguity about right or wrong is necessary here. It exists when finding bugs, but not in more subtle things. For example, asking a junior for feedback as a friendly gesture and exposing him to an interesting problem. If he then takes the opportunity to one-up by explaining his naive opinions about irrelevant details, do you ignore him? He will experience it as being marginalised or "gate-kept". The problem is that youngish guys have so much ego invested in feeling smart.