Are we talking about the regular old anger that all of us feel when we don't get what we want? Or is this a more complicated anger, based on not being able to help a patient (as some other people mentioned)? This is a really important distinction IMO. I am ok with having people angry at me, but not getting angry over every little thing when it doesn't fit their idea of how reality should conform to their wishes. Yes of course, we all feel irritation or frustration when people don't follow our advice. But part of the learning experience for me of therapy is being around someone with the emotional maturity to look at their interactions objectively and I feel like it kind of detracts from the lesson if a therapist shows a lot of anger over relatively petty things.