Why are hookers looked down on?

sometimes i do think like that, but again, after i went down with her on some social service project, a realize that even they're on such poor economic difficulties, still they have choice. That economic difficulties ussualy just their justifying statement for themself and for others, so at least they have some reason so that other won't looked down on them. I put my pity on them (hooker) since they have options, they can choose ... but they choose that ... (different cases with underage hooker that sold with other person, kept in prison illegally, and many other conditions that makes them have no choice because they can't escape / forced by someone else. Under that circumstances, i won't look down on them. So it depends on the reasons ... do they were forced to do that ? (raped, blackmailed, kidnapped, etc)