To me I like to think of pride and shame being opposites. And if you were to ask me if I'm ashamed to be white my answer would be categorically no. But if I'm proud of it? I think I am but I'd be inclined to not say it publicly because of what people would assume from me saying it.You are right to state that it's hard to define but The way I see it, and it's only a matter of opinion, like most things it's in the context. To say someone is "proud" to be white, sounds very derogatory and suggests that their is superiority.