Managers with negative attitude who make you feel incompetent.
They hire people who have no teaching experience, yet they expect you to know everything and get angry if you make a mistake. Please retrain your supervisors and managers to be more patient and professional to the employees, not just with clients. It's a learning environment for both the students and clinicians, and responding in a condescending manner only makes the clinician more nervous, and overall make it a negative learning environment.
A positive attitude and kindness is everything. Body language says a lot and even if what they say is not intended to come off as negative, it does. Remember, good customer service is not just for the families, but for the people who take the time to teach the students.