I'm a nurse (retired now) and worked in a MD's office. Doing EKGs was one of my duties. The patient had to recline on a table. We had one lady who had the same style shoe in many colors and never got them mixed up. She always wore her shoes on the wrong feet. Knowing that, years ago, that was a treatment for certain foot problems, I never commented. Finally one day I asked her what the problem was that caused her to do that. Her answer, her vision was so poor that she couldn't tell that they were on the wrong feet but she did thank me and said that she had wondered for a long time why her feet were hurting so much. At every subsequent visit, she had her shoes on the correct feet. We laughed together about it at every visit.