Haha, depends on a lot of things. A c*nt's a c*nt wherever you are and will more than likely be treated that way anywhere.
Normal people will be treated normal and as I understand it, Aussies are generally quite friendly. That said, if that cliche type of loud, obnoxious American who is sure the world is revolving around him steps onto the scene, he will not win fans anywhere, not just Australia, I suspect. And sadly, they do exist. Honestly, not really met many Americans but far as I know the ones I have have been nice people. All up to the individual, though, I guess.
No we are all loud, obnoxious, think the world revolves around us(doesn't it) and most of all arrogant, all things I believe the Aussie women will love, but I am working on my Aussie accent, hopefully by the time I visit, I will have it down, and nobody will no the difference, until after I nail them, then I will quickly convert back to my american voice(since we dont have accents) and split the scene, you should be ready Geoff, since your helping me, dont think im ever going to Sydney without dropping in on you, id have to be a bloody fool mate.
Just keep watching those Crocodile Hunter reruns, and you'll be fine.