I agree and its an absolute minefield knowing what is and what int acceotible these days. I was told quite clearly by a west indian friend that it is correct to refer to people like her as black and definitely NOT coloured (though not so long ago that was the politer thing to say.) But now I often hear the phrase 'people of colour' - how is that different from coloured? Also its difficult if you don't know where people are from to know whether to say W Indian, African, Pakistani, Bangladeshi, Indian, Sri Lankan etc. Easier to say black or Asian but none of us (I presume) wants to be offensive! Anyway many of them are British and born in Britain so to say where are you from is also inappropriate!
I also had a black colleague who thought it was ridiculous to avoid the word black when it was simply descriptive as in Baa baa black sheep, black board, black coffee -in fact he always asked for black coffee! If the term is derogatory as in black sheep of the family, little black book, black mark, that's a little different.
I also never uderstood why Obama was always referred to as black!!