So, because I am how I am, I asked my therapist who is a trained trauma specialist about this. She was uncomfortable with the idea of pushing a client for details, and with the idea of trying to "test" the veracity of what a client tells her. She said she has a hard time believing that either action wouldn't negatively effect the therapeutic relationship, the client's ability to trust their therapist, and the client's well being.

I tend to trust her, but keep in mind I am biased. She keeps a Yoda, Chewbbaccaa, and C-3PO doll in her office as a visual for describing different "minds"- wise, emotion, and analytical. That level of nerdiness increases my tendency to trust dramatically.