No. The term "stripped receiver" means that the Lower Receiver does not have any parts assembled to it. It's just the LR itself. However, they do have the protective finish.
Now with that said, some are gray & some are black. And there's been a lot of interest in painting them, along with the rest of the rifle. Admittedly they look pretty good in many cases. I changed mine from gray to black some time ago. Some of the black has worn off and, any more, I just don't really care.