Please re-open Why (and since when) is prostitution called “the world's oldest profession”? . Talking about a well-known euphemism that's used in polite company (even Ronald Reagan has referred to the phrase!) shouldn't be closed because the subject matter is somehow "dirty".
After I had voted to close the question, F'x contributed some good edits. I have since voted to reopen it, since I agree that tracing the history and usage of the phrase is appropriate and on-topic for this site.
I think the question could be made even better and more obviously on-topic if it were written such that it could be answered by a post such as F'x's, or something similar, if you found his objectionable. Perhaps if you edited it like that, more users would agree that it is on-topic.
It doesn't seem reopenable to me. It wasn't closed because it is a taboo subject: it is pretty low on the taboo scale. It was closed because it is not particularly substantive about English -language-. It's a question of sociology and history and humor, not language.
Did you have an answer to give to it? Then I think you can still answer or put it In a comment there.
Are you curious about other answers? I think one of the answers there actually does trace the history as well as could be done, so no need for more of the same.