Each person has its own way of doing things.
Now you get this lesson, then you will know how to treat other pre-dental students in the future/when we are a dentist.
Dont let a single dentist get u head down. There are plenty great dentists around. My feeling is that the older or more experienced they are, the stronger bond they grow with their patients. Thus, their patients are more likely to get disturbed from other students shadowing. In addition, they have so many stories and experience to share. The experience is inbelievable.
Wish u all the best on your second try.