I've found that most of the casinos don't mind, and it does give the player a little better fighting chance to know the other cards, or really to be able to know what is left in the deck.

Say you are sitting on a pair of 3's and the dealer's up card is an Ace. If the table is full and nobody else has an Ace, then the odds are higher that one of the dealers cards is an Ace. But if all the Aces are in players hands, you are guaranteed that the dealer's up card is going to do him no good (except for a possible straight or flush).