As a rule of thumb, if a 19 year old, who's clearly fit and don't have problem getting laid otherwise, is working as a prossie, she's doing it for a quick buck.
Those who are doing it for a quick buck, don't give a shit about the service, is not sincere, don't care about long term reputation, or the punter and his feelings or money.
I don't know about others, but it's a costly hobby, and for me, I don't like wasting my cash on girls, who are just there to nick some paper out off me.
That, and the fact that she's choosy about which ethnicity she meets, and uses far too many "lol"s for my liking.