...i call 'white people' caucasians for a more formal term, and as of yet have no clue how to call 'black people'...[i do say black out of ease and due to inaccuracies of other terms]
the reason why i *don't like* to use colours [not formally] is because i wouldn't call someone asian yellow, an indian brown, a native american red and whatnot, it sounds like the colour palette of a nightmarish painting, plus the added complication of a wide range of skin colour spectrum in each of the race. Besides, it just seems very uneducated and narrow minded to point and name a colour. Using formal words demonstrates a certain willingness and openness as well as respect to cultural diversity. It doesn't have to go to a point of extreme political correctness, but if there is an accurate word for a certain race/ethnicity...use it. It makes a person sound a lot less like a dumb hick.
Anyway, it's not really a matter of being offensive so much as a seeming like a dumbass that i'd prefer to use a 'proper' word. Although at the end of the day, it's where you hold your citizenship. So that makes me Canadian no matter what the skin colour.