I was signed on as a model by woman art instructor who looked me over and said she liked what she saw. Once I was on the roster at the university, they had to hire me when I wanted to work and I got more work than I could take. It is true that being on time and a good poser goes a long way toward keeping you employed.
Here is my cock-bias story -- I was posing for a sculpture class. Reproducing the model's body exactly was part of the exercise. I posed class after class in the same pose. Holding it exactly, throughout the class, and returning to it exactly after breaks was quite a challenge. The class had even more attractive girls than usual and I enjoyed them studying my body so closely, however, One day when the sculptures of me were coming along, the older male instructor came up and stood behind a good looking dance major who was sculpting right in front of me. He said, "you are making this very true to the model... (Pause) I should tell you that in classical sculpture the size of the 'pudendum' (means genitals in Latin) was usually made considerably smaller than his (my) large size." She said, "That's ok I like his the way it is." The instructor, stood by a second looking over to me to see if I had heard. They were quite close and she had spoken loudly. I kept looking in another direction until he turned away. Then I looked at her and we locked eyes and smiled at each other. She was one more "date" that I got from modeling.
I have scanned some polaroids of me in that class (used when I was sick for a few sessions) and they are in my gallery. I have written up some memories of my time modeling in school and for private classes. If you want to read them let me know.