All these warships in space should be coated/clad in a material that will camouflage them in space. Interestingly theyd be cloaked in something that would inhibit detection in the UV+ bands and IR- bands, since any data entering a sensor will be greatly red-shifted or blue-shifted by motion. Enterprise gets a pass because it is a vessel of scientific exploration.
When these spacecraft are shown moving through space, what is the source of illumination? Theyre typically light years from the closest stars.
Admittedly adhereing to the two statements above would make for TV that is difficult to watch.
The enterpise actually also had two different colour schemes. They repainted it for Generations to a blue theme with more detail for the big screen. The series one had the greener “aztec” details.
Basically colour in trek are whatever the person doing the post work decided and seems to have little to do with the studio model. The lighting tended to wash everything out anyway. Pedantry aside (I do like some good pedantry) the Warbird will always be green (screen apprearance) to me.