Ballet Prostitutes

Ballet dancers probably have less than ten years at their peak performance, because of the intense muscle demands of their profession. Professional athletes can extend this to a number of decades. An engineer can typically continue working and improving herself/himself until retirement ages. Actors' spans vary greatly depending on the paths they take, as do other entertainers.

But how many good years are there in the career of a prostitute? That is, how much time do they have before their looks and body (which are the sole "talents" involved) deteriorate to a point of non-income generating?

* I should note that I am neither condoning the professions labeled here, nor poking fun. Simply a question of wonderment.