You know, I often hear the "we lack manners" statement from Americans, and I never get where it's coming from. I suppose it all depends on who you compare with, but in my own limited experience (I've worked and traveled in Australia and central Europe) Americans are generally the nicest people I've ever met, in terms of everyday kindness and courtesy.
Lacking manners and being nice are different things. Yes, generally Americans are nice people. But when at the cafeteria I see people chewing with their mouths open, I often see guys cursing in the presence of women and children, and I see people violating basic rules of etiquette wherever I go.