Anger is also inappropriate when it is allowed to fester. Wholesome anger should be short term anger. If you can't let go of the anger producing trauma of the past, you're the person who is going to suffer the most from it. If you don't rid yourself of anger, it poisons your system. It saps your energy.
Anger is inappropriate when it is result of our impatience.
It usually doesn't pay when we give way to anger just out of sense of frustration and impatience. So anger is a mixed bag. It's not always appropriate to feel guilty because you're angry. I grew up on the farm and we usually had cattle and horses. My Dad sought to impress on my mind how important it was to keep the gates in the pasture closed.