I think that some people might get confused about what is current terminology. We all should know that 'coloured person' is offensive but people who do know what is and isn't correct use 'person of colour' which is not.
And yet, there is very little difference between the two. But your common sense tells you that one sounds more respectful than the other. However, before "person of colour" became the correct nomenclature, calling someone a "coloured person" appeared to be more polite (or less offensive) than calling the individual "black" - but now it's acceptable to use the word "black"... as in "the black community" - if, for example, you might be talking about social issues / poverty / education, etc.
Of course, if you know someone's name - there's no need to refer to skin colour at all, you can identify them with it.
The PC and non-PC terms change so frequently older people can be forgiven for not keeping up especially if they are not out at work keeping up with changing terminology.
One of my black / person of colour / 'native' friends, during a social evening in the pub when we were discussing this gave a couple of eye-rolls at the knots people got into trying to be (and I hardly ever use this phrase) 'politically-correct' (he used it). He said, basically, he knows when people are being racist and discriminatory on the grounds of his ethnicity... and he hardly ever comes across such a person! Which is good to know.