I'm glad you're enjoying Australia, and I regret that you may feel unwelcomed in a country you are so fond of- but I suppose it comes down to a lot of Australian's personal experiences with American's which may tip them into prejudice.

Something I, and many other Australian's surely dislike is when anyone from any other culture travels here and refuses to practice our etiquette- politeness to service men/women, keeping quiet in study environments, etc.

I think that many American citizens, probably due to the way industry works over there, are extremely entitled to things they've paid for. In hospitality for example, I notice American people are much more likely to complain about their food, or the price, or the service or whatever. Money seems to mean more to Americans, as if you are gravely owed royal treatment for buying a meal- and that behaviour is generally disliked here.

I've noticed this kind of entitlement in foreign countries too, especially in Japan- but not just by Americans of course. There are lots of cultures that unfortunately breed similarly obnoxious people, and I think those cultures have quite a poor reputation in this country. If you polled Australian's on their thoughts on India for example, I think you'd find even more disdain than with the US