I guess I wasnt thinking things through.
I kept considering what you said and now I no longer think its worth to add tags for tails, horns and so on. Its better to have that small odd-ball group of demon images without horns show up, even though the npc has horns, than it is to overload the mod with scans. Either that or not add those images in the first place, but as long as their race is clear its not really a problem.
As for images that have non-standard race colors I still believe its better to just tag those and add them as they are.
There are not many packs yet, not many pictures either. Its better to start tagging them with the eye color tag from now on and re-tag the existing ones whenever its possible. Probably something like "YellowEyes" would work.
Thank you for opening my eyes on this.