The only thing that is a total no-no for me are sunburst finishes.
I don't like black or white finishes either, though I would make an exception for a black/maple neck Precision or Stingray.
My other "most hated" finish used to be Candy Apple Red, but I've just bought a Stingray 5 in CAR that I think looks lovely, though it is a lot darker than many other CAR finishes I've seen.
I generally like to see blues, greens & purples used as they're still fairly uncommon.