Some people would say drinking alcohol is immoral. Smoking cigarettes is immoral. Calling in sick (and playing hooky) is immoral. Putting in a half-assed days work is immoral. Lying to your mother is immoral. Cheating on your wife is immoral. Having sex outside marraige is immoral.
Different people embrace different moral rights and wrongs.
To some people in the world, prostitution is a normal job, like driving a bus. To many American people (even some on this board) it's a sin.
Each of us decides what is the right way for us to live, so we can sleep at night. That doesn't mean it's the "right" "correct" or "moral" way to live, for everybody. But it's right, correct, and moral for that one person.
I will admit that hurting someone else, for one's personal gain, is a universal wrong.