I've written about this before, but I'll go over it again:
Yes, the rules of poker specify that you can ask to see any hand that goes to showdown. But, in practice, asking to see a hand once your opponent concedes is bad etiquette. You are saying to them, "I believe you are colluding with others at this table and need to see your hand to prove it."
If you are comfortable with accusing another player of cheating, then by all means, ask to see the hand.
If you're not then shut the fuck up, take your chips and play the next hand.
Todd.com, Todd Draper's Weblog.
