Sometimes. It's more common to find free trials, satisfaction guarantees and refund policies when you choose an online personal training platform. In-person trainers usually charge as you go; you wouldn't get money back for training sessions that already happened, but you wouldn't have to pay for future sessions if you were unhappy with the service. And, of course, no personal trainer is going to guarantee specific results - since what you do the other 23 hours of the day is going to have a big impact on your success, beyond what you accomplish in your personal training sessions.