Hm. See, I always found that in DBZ Goku (to me) was white, like most of the characters on the show. However, I think it's mostly viewers perception.
I didn't take their clothing into account, but more so their way of being drawn. It seems to me that on anime shows, those who are meant to be asian are drawn with exagerated asian features. (For example, Brock from Pokemon) Since that was what I had always thought, I kind of assumed that almost all of the DBZ characters were supposed to be white. But I am white as well, so I (as a child) probably just thought everyone was ''like me''