. Note I specifically include heterosexual here because it cuts both ways. A gay man could still be gay not bisexual or heterosexual despite having sex with exclusively female clientale. A heterosexual man is not gay or bisexual simply because he has sex with male clientale. The same with women of course (there are definitely lesbian prostitutes who have sex with men.) N.B. JC you're right that part of an individuals sexual orientation is who they choose to have sex with. But it's not the only part which is the key thing your missing. An individual who as part of their work (or for that matter, for other reasons e.g. career advancement), has sex with someone but does not feel any attraction to or erotic desire for individuals of that sex is not by most definitions homosexual/bisexual/heterosexual because of their work.