My mother teaches English as a foreign language. Throughout the summer she has had students staying with her.
While I was there this weekend, a French student arrived. When she came in, she asked if she should remove her shoes. My mother explained that she would need to remove her shoes before going upstairs, where there was light carpet, but she could wear them downstairs where there is wood flooring.
So my mother is currently in the 'no shoes upstairs' camp.