I don't usually have issues being assertive when necessary so did not have a need to express raw anger to a T that I could not vent anywhere else. But I told one of mine many critical things, both in person and via email. I personally prefer to be direct and express what exactly I am angry about instead of just putting feelings into words. For example, I told my first T that he was unprofessional, manipulative, projecting things onto me that had nothing to do with me, and that it is unacceptable that he couldn't fill a simple insurance form properly multiple times and can't keep track of my in-advance cancellations that were clearly made in writing. I usually find this type of expression more useful with anyone when there are repetitive issues, simply saying that I am angry or hate them is not so productive IMO. I also personally would not say that I hate them to anyone or swear at them, that's beyond what I consider acceptable communication on my end. But apparently many people find it helpful to be able to say such things. My incompetent therapist always preaches how a T should be able take anger from a client but he could definitely not handle my criticisms well. He often reacted very emotionally, more like a hurt kid than a civil adult, and it really shocked me at first as I had never seen similar from other people. Kinda roles reversed, but I think it was really inappropriate from a T. I speculated that he perhaps reacted so strongly because I very directly expressed real things about his incompetency, not just some transference type anger that he is probably more used to. But I think it is acceptable to express dissatisfaction with a service I am paying high $ for. I was never angry (or otherwise negative) with my second T, he did not do anything to make me feel that way, just concluded in the end that therapy was not useful so I left.