Dear John: M.D. commented on how the behavior of a bartender differs depending on whether he/she is being observed by the customer.

I would add that in some restaurants, the server delivers the check to the customer within a folder, into which the customer then slides his/her credit/debit card.

The server then picks up the folder and takes it to an employees-only area in the restaurant, where he/she swipes or inputs the card. But while the server is holding the card, he/she also is able to copy all the card’s information to sell to a bad guy, who can make unauthorized purchases. D.W.

Dear D.W.: Geez, isn’t there any trust anymore in the world? The waiter could also put poison in your food. That’s really something to worry about.

Having said that, I once did get my card information stolen by a food delivery guy, and the crook purchased a dozen soccer balls. The credit card company never disputed the fact that it would not be me who’d made such a purchase. I guess they know more about me than I thought.