Selling/buying sex has always happened and as long as our society doesn't completely change it always will. I think there's nothing wrong with prostitution as long as there is a solid legal framework in place; a framework that can protect both the provider and buyer of said services.
Like with most things, banning it or making it illegal doesn't make the thing go away, it just pushes it into the underground, where people will be trafficked and abused.
In my opinion prostitution should be legalised and recognised as a profession. The state can gain through taxation, the workers gain by having their rights as workers upheld(sickpay, pension etc ) .
*A note on your post, you might want to edit it as it seems you've pasted the same text a few times.