It's a challenging place to be when one is expected to always know how to fit into the role that different types of clients want their models to represent while representing their brand. Most models are still young and learning about the industry (and life) as they go.
The best clients offer communication while the best models know that they need to have more than one aspect of their personality ready to shine at each booking.
The secret is to accept that NO ONE MODEL can fit into every role within the industry. They should "fine tune" the skills where they can specialize in the "TYPE" of modeling that they like and excel in. That increases the chances of success and personal happiness in what they're doing because rejection, critique, negative comments, etc. will be out there for every model in the industry.
It's not impossible to keep a positive attitude about themselves, but it's not always a good career choice if a potential model isn't ready accept the way that the business and industry professionals are...that they're sometimes NOT professional. Regardless, the model should not think that they'll get very far by being unprofessional like those few "bad apples". The goal of the finished project is more likely to have success with collaborative effort and guidance from communication and effort.
Sometimes, though, things just might not work! How one moves on and puts an effort into not letting the bad jobs define their career are the ones most likely to succeed in keeping a good attitude while they are in the industry. Those skills will even help if it's time to "leave" the industry.