re: Poker & Q : I have the winning hand in Hold'em...
Yeah it's considered rude to ask to see mucked cards, however each card room has different rules as to whether they will show the mucked cards or not.
Just do this...if you 'paid to see them' that typically means you called a bet. You do not have to show 1st. Most savvy players will wait to show their hand if they think they may be beat or if you are willing to just flip them over. When they ask, 'What ya got?' just reply, 'I called you, what do you have?' they then must show or muck. If they throw their hand straight in the muck, the dealer should start pushing chips your way and you probably do not have to show either. I wouldn't. The other player may bitch (which he is now in violation of this 'not showing a mucked hand' etiquette rule), but he mucked and his hand is dead, you were the last hand standing so you win. Let him cry.
The game is about incomplete information and players learn to steal as much info as they can when they can. Learn the tricks and only show when you HAVE to (or want to).