I have, on a couple of occasions, been given to a different trainer.
The result, in both cases, was: "I don't understand the problem; he seems OK to me."
Sometimes it just is a personality thing. I remember a guy I flew with as his FO and was, years later, in another airline, checked by him as a captain myself. I didn't like him the first time and it hadn't changed the second time.
Why? I have no idea; couldn't put my finger on the reason. Just thought he was a weird cove.