I like what Anne said above about communication. I did not use my therapy in that way but practice very similar awareness and approaches in my everyday life, in all sorts of relationships.

I think there are therapists who are very solid and well-intentioned and there are also insecure, defensive, manipulative ones. I do not believe that anyone can regulate their moods at all times though (I think that idea that a T can keep their crap out of their work all the time is an illusion) and if someone's reaction feels disturbing and it is important, it is best to discuss it openly. Same about our own reactions and how others see and interpret us. Usually I find out from those kinds of discussions quite quickly if someone is stable, open and generally doing their best and perhaps just had a bad day or misunderstood me, or it's a chronically insecure, defensive, unreliable, close-minded person. The way someone reacts to feedback (both positive and negative) can reveal a lot IMO. I personally don't like to communicate merely expressing anger and frustration (the emotion) as I rarely find that productive, I prefer civil, non-impulsive dialog. Of course can't say I am always able to pull it off but it is usually a rewarding and constructive experience to try to interact that way.