For instance, Kirk's velour tunic in the first two seasons was actually avocado green like his wraparound tunic, but it photographed as gold because of the way the material reflected the bright stage lighting. So we can't assume that the way something looks in a photograph is a reliable representation of how it would look to the naked eye.
Same thing with the monster makeup in the old Universal FRANKENSTEIN movies. Originally, the idea was NOT that the monster was supposed to have green skin. They just used green makeup on Karloff because it photographed as a corpse-like pallor when filmed in black-and-white . . . which fit with the idea that the Monster had been stitched together from pieces of dead bodies.
Somehow, though, the idea that the Monster has green skin crept into the public consciousness, which is why the Monster is painted green on Halloween masks and toys to this day.