I have nothing against repainting machines that need it. My only gripe is when someone does not bother to research what they ended up with, and that beat up old Singer was very collectable in the worn shape it was in!
I ended up with three machines like that, I bought them cheap planning on repainting - but after doing my research, realized I'd ended up with something rather rare, so I decided to leave them as they were.
Machines like that aren't all that common, most will have their value greatly increased with a new paint job.