There's a glossiness to rich USians: I'm guessing it's to do with what you mention -- haircuts and clothing and access to cosmetic dentistry. (That US equation of 'bad' teeth and 'crooked' teeth always squicks me, as it's so rooted in money.) I have the sense US class it more directly connected to money than UK class? Here, people can be seriously wealthy and yet completely working class, or poor and middle or upper class. (The really poor are always treated as an underclass, whatever their origin, which is despicable, in my view.)