I've heard about this from my parents. When they were young, in the 1920s and '30s, and perhaps even later, Black people were not allowed to try on shoes. They had to buy them. You could not go into a shop and try on a hat - you had to buy it.
To read more about this, see "Dr. Ambedkar, Visionary".
See also: "Black Facts" in Black History International.
This is similar to what Winnie Mandela described as her experience under apartheid in South Africa.
But recently, I have read that a customer would trace his or her feet on a brown paper bag, then bring the drawing to the store to indicate what size of shoes they wanted.