Wow.
I had rotator cuff surgery on my right shoulder last August. After I had dis and re-robed, I was sitting in an easy chair for surgery prep. A really sweet nurse came up and said 'I want you to point with your finger to the place where we are going to be operating today.' I smiled and pointed to my right shoulder. She pulled out a sharpie like thing and wrote something there and initialed it. I can only guess it had that brown iodine disinfectant for ink. I told her I had had a thought about this but wondered if it would be rude to bring it up. She smiled.
This happened twice more, the final time with the anesthesiologist. I said I was aware, and no doubt she was as well of people have the wrong foot, etc. amputated. She gave me a serious look and said "not in my room."
Bay area baby!