As an outsider, living in a rich little island in the Caribbean where many Americans come to work, or on cruise ships or to charter yachts, its very easy to see the differences between the classes and who would mix with who.  The snow birds who own winter houses here are often (but not always) people from 'old money' or boast about having antecedents who came over on the Mayflower and they are snotty in the extreme.  (Those who made their money and own houses are sometimes snotty and want to mix with the other group only and sometimes not).  Those who charter are middleclass, usually professionals.  The cruise shippers are almost all working class or lower middle class, very rarely professionals. They are immediately identifiable by their clothing - they visit 'resort' departments of stores I think, wear polyester, matching tops and shorts, clean white trainers and wear jewellery and makeup with their swimsuits.  They tend to not to want to know any locals (blacks) and like to bargain for everything. They, out of the three groups, tend to have more obese people in them.   The middle class ones rarely bargain (everything is fixed price here) and like to know the locals.  The upperclass lot don't bargain either and only mix with locals who are government people or lawyers. 

Class is something all British people can identify instantly, and once you are familiar with another culture, you can point out the differences in their's too.  None of the class things though tell you anything about people's personalities or characters only about how they behave abroad on vacation where the differences are very marked.  When I am in the US, I can't tell as easily, except by occupation.