I guess the best thing is first do your homework, then listen to your big head at the start of the session so you can back out. Of course there will still be circumstances when things go downhill after the session started. If it is due to a clear case of being lied to on service provided, I see nothing wrong with demanding a refund for service not provided, drama or not. If it is more of a chemistry thing, write it off.

In either case, did you write a review?