You can make boots white if you fail the coloring, I think it is. also depends ont eh boots i'd imaging but not sure on that.
I've got a pair of white boots myself. I'm pretty sure it's not because they're white but simply because the color failed.
If I bleech them they will turn greyish. But it's hard to tell what if at all they were colored with but they are pretty white.
They look like the boots in one of these pics but are skinned. but might be a bit whiter not in game to tell.