Yep I struggle with this big time!
My T will say something and in the back of my mind I'm like "your just saying that because it's your job"
like a therapist always goes on about how "being genuine" is important in the relationship but it's not like they are going to tell you how they really feel as it would most likely crush an already crushed self esteem.

I think it's more about trusting that they do in fact have your best interests at heart and drawing on previous expeirences and reminding yourself that they are ultimately here to help.
It always helps me to tell T what I'm thinking and kind of reality test, just to level myself back out- I struggle with remembering what a healthy therapeutic relationship is like, so by asking I can figure out whether i have unhealthy and unrealistic expectations happening.
The unfortunate part is that there are always going to be those times where we question what they and why they say things, I don't think that will ever disappear.