How would I know if I have the right therapist?

One way is to bring one's concerns or desires to the therapist directly, rather than trying to subtly 'train' them. Here's why I say that: 

One quite important healing factor in a psychotherapy is discovering that problems in the therapy and the therapeutic relationship can be solved together. 

It is a safety zone or bridge for practicing that. If it can be done with a trained, usually safe person (the therapist), the client might think, wow--what are the implications for my outside life and relations? Could I get what I want outside of therapy, too, even if it feels not as safe?

If the therapist can deal with feedback (and any good therapist should be able to), this can be very productive. Cooperation in this way, in the moment, with a live person who is supposed to have authority and knowledge in these matters, can be profoundly healing.

If the therapist can't take feedback or doesn't want to--or does nothing to act on it--maybe we could say the client has the wrong therapist.