Nothing wrong with nudity in my humble opinion so long as it is in an appropriate setting like a nude beach or on private property.
As regards the general beach scene I have noticed a distinct lack of topless girls around Perth and this is a pity. My understanding of the law is that under Council by-laws it is forbidden but enforcement is left to the beach inspectors. They can ask a lady to cover up but they have no statutory power so if she refuses they must contact the Police whond jku can arrest her. In other words, the Police will only act if a complaint is made.
Of course, if a man dropped his tweeds on the beach that would probably cause a lot more fuss.