3-card
I don't remember where but somebody did run a sim on this idea and found that you can get sometimes gain an advantage, but infrequently, and with the normal 2-3% house take, you would have to spread your bets by more than the table limits.
If they ever dealt straight 3-card poker out of a shoe, then the regular bet would be very countable. The banker gets her advantage when neither hand has a queen. You fold (bs) and the banker "folds", but the banker wins the ante bet. The player get his advantage with the bonus payments for straights, 3-kinds, and straight-flushes. A deck rich in Q,K,A means that there are far fewer situations where both hands fold, and a smaller effect on the bonus hands (a sim would help here). But the inventors probably thought of that, which is why they only play 1 round per deck.
I read somewhere else that there is an AP in LV who does in fact earn money off this. He must have found a favorable game somewhere.