a go-to-hell air and black number - what does this mean?
Here is an extract fron the book and I don't understand the sentence with "go-to-hell air" and "black number". there’s a go-to-hell air about it that doesn’t attend the prudent black number - what does it mean?

After extensive and really quite impressive research, John T. Molloy has discovered that in raincoat colors beige far outranks black, olive, or dark blue. The black raincoat proves to be, indeed, a highly trustworthy prole sign. Thus Molloy exhorts his prole readers ambitious to acquire an upper-middle-class look to equip themselves with beige raincoats as soon as possible. The implication of beige, one supposes, is that it advertises one’s greater carelessness about the risk of stains: there’s a go-to-hell air about it that doesn’t attend the prudent black number. You will not be at all surprised now to hear that in I Love Lucy the raincoat worn by Ricky Ricardo is black.

Question

a go-to-hell air and black number - what does this mean?
Here is an extract fron the book and I don't understand the sentence with "go-to-hell air" and "black number". there’s a go-to-hell air about it that doesn’t attend the prudent black number - what does it mean?

After extensive and really quite impressive research, John T. Molloy has discovered that in raincoat colors beige far outranks black, olive, or dark blue. The black raincoat proves to be, indeed, a highly trustworthy prole sign. Thus Molloy exhorts his prole readers ambitious to acquire an upper-middle-class look to equip themselves with beige raincoats as soon as possible. The implication of beige, one supposes, is that it advertises one’s greater carelessness about the risk of stains: there’s a go-to-hell air about it that doesn’t attend the prudent black number. You will not be at all surprised now to hear that in I Love Lucy the raincoat worn by Ricky Ricardo is black.

Answer

To have an "air" about something means to posses a certain quality.

Go-to-hell basically means, I don't care about you/it. I would say it comes from not caring about whether one ends up in heaven or hell in the afterlife, and perhaps even how quickly they get there!

In the context of the passage you have provided, it seems that:

People that wore the beige coats didn't care if they got their coats stained as they were supposedly so rich they could afford to buy a new coat. Having a light-coloured coat therefore became a sort of social status symbol.

The "black number" is the black coat. "Number" is often used to describe an outfit or piece of clothing.

They have used the black coat as an example of what less-weathly people would wear = a prole sign, or sign of class.