The Other Brahmins by Dr. Adelaide Cromwell addresses this directly. It is a study of the Boston Black upper class from 1750 to 1950. She published it roughly at the time of her retirement, and it is a reworking of her original doctoral thesis iirc in 1946.

Her career was a long list of 'firsts,' being a black woman holding a PhD and teaching at mainstream (not HBCU) universities.

To make a very long story short, the white community made little distinction between professional, working class, and poor blacks. Black families who considered themselves solidly middle class or elite were emphatic about maintaining their relative status (think of Hyacinth Bucket in that British sitcom!) among black peers, while the rest of us would have seen little difference. The black elite was very insular. Their snobbery was different from white snobbery in subtle ways. Your wealth was a little less important, your coming from a 'good' family was a little more important. Membership in formal social groups was more important to the black upper class (e.g. college fraternities, sororities, the right church, Elks or Masonic lodge, etc.

Black professionals were in a narrow set of professions where they provided some kind of professional service to black clients in jobs that white people were less likely to take over - black clergy, teaching, realtors to black neighborhoods, small and segregated businesses.

She even has detailed survey data on how discretionary income was spent. Comparing white and black middle class families mid-20th Century with identical household income - the black family had a cheaper home but a better car. When a TV was new tech costing a month or two's wages, black familes spent more and earlier than the white family of similar income. IIRC, this was due to more entertainment at home instead of nice restaurants or the country club they were not allowed in, or were not especially welcome when they were allowed.

There is a whole book of anecdotes but this is getting long already - go find her book!