According to the rules of the casino, all cards must remain on the table. The dealer is permitted to deal only with one hand and cannot lift the cards off the surface. In other words, they are not allowed even a fleeting glance at the value of the cards. They must lay them flat on the table for all to see.
However, this does not eliminate the possibility of cheating. At the moment of revealing the cards, dealers can utilize sleight-of-hand techniques, such as the 'cloud sleeve' maneuver, swapping cards that have been discreetly hidden in their cuffs.
Admittedly, such a feat is fraught with challenges, particularly when performed under the scrutiny of multiple observers. Nonetheless, those accustomed to serving undercover roles in the casino possess a skilful touch.