I think this is a really complex question. If I look at my own work as a teacher, for instance when I teach English oral proficiency, I know that some of the students I teach are going to become much more proficient, some of them are going to improve their English just enough to be able to communicate a bit more easily with their teachers, some of them are not really going to improve at all, but may become more confident in their own abilities to speak, and so may go on to improve once they are outside my classroom - and all these students might actually have benefited from my teaching. So what is important here is that I don't apply my own notions of how they ought to improve, and think that a student is hopeless because the improvement is not what I think it should have been. I can tell a Spanish student that she needs to learn how "b" and "v" are different in English, because I believe that unless she knows that, it will make it more difficult for other people to understand her, but I can't say, or think, that if she leaves my course still pronouncing "berry" and "very" in the exact same way it means that the course has been a failure for her.

But there are students I can't help, though somebody else probably can, through encouraging them in a different way, or offering different exercises, or whatever. And we all know that all Ts don't click with all clients. So to be honest, I think that a T who hopes that s/he or the therapy s/he offers will work for everybody who comes to their office is both arrogant and naïve.

Besides, what about those people who genuinely are beyond hope? (Here I am thinking of certain mass murderers, for instance.) Should they be denied therapy because the therapist needs to feed their ego by thinking that they (the T) should only be required to treat those people that there is hope for? As I said, a complex question.