Not sure if I agree with that. A layer of paint does not a prototype make.

Well... Okay... Sometimes it does...

For me, it depends on how different the prototype is from the main production model. Sometimes they're nearly identical and sometimes there's quite a difference.

For example, simply taking an early short-barreled Panzer IV, painting it with primer, and calling it a prototype does not do it for me. There has to be a more substantial difference - a reason why this particular model is a prototype and not just a production model with a sloppy paint-job.

Of course, that's just my opinion. It's not even my competition, so who cares?