I love painting white dogs because you really have to paint the nuances.White forces you to observe the colour since nothing is really just white. On the other hand, one should be doing that with any painting but it seems just more fun with white. Look at Ray Kinstler's portrait of Tom Wolfe. It reads as white but of course there are a million pastel shades. I love this painting but alas only from afar - I have never seen it in real life but I am sure it is even more wonderful.