If they're a full-on toady windbag like Vance, it doesn't matter which party they're from.

Not very, because Vance isn't very old. When was he in the KKK? It would be very unusual to be in the KKK in, say, 1995. Someone would have to be extremely committed to white supremacist ideology to be in such a position, I would think.

Still pushing stories about Haitians and cats?

Probably not. Even if - as in this case - it was 30-50 years later. (That Biden said kind words about Byrd)