Dogs come in all shapes, sizes and colors...
Look at this photo of a Chinese Crested Dog... they are completely bald so it shows how a dogs skin can look much better than one with fur!
They have pigment that can range from the entire dogs skin being white, to the whole dog being grey, to patchy like the one in the picture
How old is your dog?
Have the spots always been there or are they new?
Are they just colored spots or are they raised/lumpy?