If I was decribing someone I'd do so in terms of their appearance and their behaviour, and try to get that as accurate as possible, not in terms of my guesses about their ethnic group or whatever, which might be wildly wrong.

Remember the "surveiilance officer" in the case of Jean Paul Menenzes, the youing man shot dead by London Police while he was being held down in his seat on the Tube after being captured, and how he identified the Brazilian as an Arab on the basis that he had "Mongolian eyes".