I too want to go to Australia. I've never been there, and it at least seems like a wonderful place.
To say that one country's citizens are rude to foreigners where another country welcomes them is just silly. People will be people, regardless of where they live. Maybe it's just the area of America where I live, but we have a very large foreign population here and I've never noticed anybody having a problem with that.
I've been to Canada about 8 or 10 times (used to go skiing there every winter), and I could say that Canadians in general aren't overly polite to foreigners. Not that they are overtly rude, and some are very kind indeed, but they didn't strike me as more welcoming than any other culture.
The notion that Americans as a whole dislike foreigners is somewhat inaccurate, I would be inclined to believe. Perhaps visitors simply misunderstand things that seem normal here, but would be construed as rude in other places. And then again, it depends on where you go. Perhaps the less touristy areas are less welcoming, but isn't it like that pretty much anywhere? I've a friend who went to Ireland for a week, and some guy in a pub was close to physically attacking her for being a foreigner (not an American, mind you, just a foreigner).
Perhaps you'd like to say exactly in what way Americans are more rude to foreigners than anybody else, from your own experiences? I'm sure I could relate just as many instances where I felt quite out of place in other countries do to my citizenship.