Long ago I was ask to judge a model contest my brother put on in our neighborhood. One of the cars didn't win because it "Wasn't Painted". It just looked like he polished the plastic body. Much to our surprise, the model was painted. White. It was a very good paint job, inside and out ( topic of another thread, painting where one doesn't normally look.).
So, this can go either way.
I've judged recent regional shows where models weren't painted, just polished.It took a second look. One did trophy.
Heard a lot on this board: "Build it your way".