Having worked for a number of American companies for years and also having traveled extensively through their country for extended periods of time, I probably have a fair understanding of their culture.
Most of what has been posted here revolves around generalisations and like most generalisations there is some basis of fact but a lot of it doesn't necessarily apply.
For example, all Aussies are blond beach goers and life saving heroes.
Many people outside have that perception.
So yes, there are some ugly American, some naive ones, some thats its easy to dislike but that apply to many nations and in most cases we dislike things because they are different or don't conform to our standards and expectations but that doesn't necessarily make it right or correct.
Another way to look at it is that whilst the majority of us are Australians, there are many American visitors to this site and some of them happen to be people I know and correspond with on a regular basis. Most of them are even regular human beings, even if they are American.
Possibly it would be more appropriate to say "I dislike what so and so has said" rather than branding a whole race with the same mark. Just my 2 pennith worth.