There's a lot of nonsense floating around about this. Some saints, like St. John Vianney, are justly held to have gone too far, influenced by the puritanical, holier-than-thou ideas of Jansenism, where sin was hiding in almost everything anyone did. The logical conclusion of this is that if you aren't saying Aves while brushing your teeth, you are probably committing a mortal sin of vanity :rolleyes: :rolleyes: :rolleyes:
Obv, if you are in public, or are around family of the opposite sex, normal rules of modesty apply.if you're going to Mass add a little extra beyond just modest, you're going to see the King! If you're in your bedroom alone or with your spouse, it's ok to wear as little as you wish. If you're in your living room, same deal, if the blinds are drawn.
There's something to be said for cultivating habits of decorum, like not wearing clothes that are too casual, all the time....... but on the other hand we're not all 80 years old, or stuffy noblemen and politicians who have a duty to always be in the public eye. Dress for the occasion. If it calls for a dress or suit, good. If it calls for a robe, or undies or shorts and t shirt, great.