What do you do when the player says he believes he saw the "color" of a card being dealt and you discover he or she was wrong? Sorry, unless the card was seen by multiple players, or identifiable with certainty, you can not expose the card.
Consider a stud game as an example; a player has three or possibly even 4 hearts on board. The dealer begins pitching the river cards to all remaining players, and someone says, "hey dealer, you just flashed Johnny's river card. I saw it, it's a red card!" What do you do? Turn it over...only to discover it's a spade? Or a diamond, or whatever.
I don't agree with exposing the card. What's to stop players from announcing a possible flashed card, only to take advantage of any situation that could: suspend further betting, or just getting a look at a players card?
RRoP Stud Rules
17. If the dealer turns the last card faceup to any player, the hand now high on the board using
all the upcards will start the action. The following rules apply to the dealing of cards:
(a) If there are more than two players, all remaining players receive their last card facedown.
A player whose last card is faceup has the option of declaring all-in before betting action
starts, meaning that the player does not put any more chips into the pot and subsequent
betting by the other active players will be on the side.
(b) If there are only two players remaining and the first player's final downcard is dealt
faceup, the second player's final downcard will also be dealt faceup, and the betting
proceeds as normal. In the event the first player's final card is dealt facedown and the
opponent's final card is dealt faceup, the player with the faceup final card has the option
of declaring all-in (before betting action starts).
