Your chances of getting laid depends on which country your from. If your from Europe or Canada, it's pretty good. USA, no better or worse. Asia, low
Africa, see USA
There are plenty of single girls here.
Yes the girls do cheat occationaly, like they do in most countries. But if you are trying to hook up with one that's in a relationship, don't pressure them, or you'll be visiting Mrs Palmer.
It also depends on which parts of Australia your in at the time. Higher strike rate in tourist area's.