I've heard that one of the common criticisms leveled at the USA by the Soviets was the terrible treatment of its minority citizens.
Given that during that time period, America would have also been trying to establish political relations with many African nations to maintain an edge over their Soviet rivals, how did they treat the ambassadors sent to them?
Copying a post I made on this a few months ago:
Segregation was a major headache for the State Department from post-WW2 until the passage of the Civil Rights Act. They spent a lot of time soothing ruffled feathers of African diplomats - it was quite common for them to be harassed when travelling between Washington and the UN, particularly when passing through Delaware. Not to mention the problems organizing things like lunch meetings in segregated DC. State advocated strongly for the passage of the Civil Rights Act because of this; they argued for it as a national security issue, since the US wanted the countries sending these black diplomats as allies in the Cold War.
A source article on this: "No Diplomatic Immunity: African Diplomats, the State Department, and Civil Rights, 1961-1964" by Renee Romano, The Journal of American History. You can access it free online.