A roué is a man who lives for pleasure — drink, late nights, and especially sex — and does not worry much who gets hurt. People use the word to show they do not like him; it is not a compliment, though in an old novel it can sound almost teasing, as if the speaker is rolling their eyes. You will not hear it much in ordinary talk. It is a bookish, slightly old-fashioned word, borrowed from French, and it usually points at a grown man, not a boy. A playboy can sound light, even admiring. A roué sounds worn and a bit rotten. Though actually the French word first painted someone so bad they deserved a cruel old punishment on a wheel, so the disapproval was there from the start.