No socks (except in the country/at the beach)
Jacket sleeves unbuttoned
giant triangle below the last buttoned jkt button - showing end of tie, beltbuckle, shirt puffing out
opera slippers worn as an alternative to standard evening shoes. the slippers were invented for gentlemen to slip into AT THE OPERA, so at least their feet would be comfortable while they sat through three-four hours of screeching altos & sopranos. the slippers are not and never were appropraite for formal dinners, dances, receptions etc.