I've posted about this before, but it's pertinent now.
I've encountered a few white South Africans who were very unpleasant in their racism. They would use the word 'blex' (ie 'blacks' in their S African accent) In Ghana (Accra) some South African hotel managers were talking in my presence about 'these useless blex' and how 'stupid they are, you can't trust a bleck to do anything properly' etc. I seethed.
And the new pupil who arrived in my classroom from South Africa and announced loudly, "I daon't sit nixt to blex!" when the only free seat was beside an Indian lad.
In these sort of contexts, the word 'black' has inherent disparaging and racist connotations.
But I'm so proud of my BLACK husband and his wonderful family. He isn't 'a person of colour' or a 'coloured person'. He's BLACK!!