The current view of the word is a product of current mores and custom, and is dependent on changing moral attitudes.

I suspect that this, like many Anglo Saxon four letter words, started out as a perfectly functional descriptor of a natural function, and therefore was acceptable to all at that time.

It is no more dirty per se than many others of the type, but perceptions have changed. I understand that there are many modern people who are just as repelled by that other long established four letter word, "work".

Don T.