I remember one of my first BA FIRSTs when a rather older gentleman, not seated in 1A, stood in the aisle and stripped down to his boxers and put on his pyjamas. I reckoned that he normally had a valet or two, and perhaps courtiers, with him when he undresses, so it was nothing unusual at all.
My rather more middle class sensibilities prevail, I'm afraid. I've always thought that although the FIRST or Club World cabins are appropriate places to sleep, they are not places for doing any number of other things that people do in their bedrooms.