This is true, of course, but I think leftist intellectuals make a fatal mistake in thinking of these traits as arising from a lack: of education, consciousness, self-interestedness, etc. So for the left then the job is deliver its message to people, which will convert them and arm them with the knowledge to fight racism, sexism, and of course capitalism. It's a messianic politics, with varying degrees of messianism.
This gets it totally wrong. Stupidity isn't an absence of knowledge--it's actively produced, like iPods and Tide. The same with racism, sexism, etc. Those things don't just exist a priori and have to be cured. They are fully constructed. So instead of generalizing about the American psyche or bitching about people's stupidity--which is also exactly what the right does*--a political act would be to try to disrupt these productions and scramble their distribution.
*It would also be helpful to stop thinking that USers are uniquely stupid, which is just an inverted expression of American exceptionalism.