they're pointless. you could just set the rendering off. making the color fully transparent will still be visible with shaders. i cringe when i see a fully loaded colorset with an invisible color because that's a spot they could have used for a much more useful color
why don't we solve this problem by making a tool, called the InvisCan. when sprayed it will turn the rendering off of a brick, like what was intended. that way, colorsets don't need to waste a space on ignorant people and we could have another very useful tool in our disposal