According to William Schaffner, infectious-disease specialist and chairman of the Department of Preventive Medicine at the Vanderbilt University School of Medicine in Nashville, Tenn., the world is full of germs. In fact, he claims that if cultures were taken from individuals walking in Times Square, roughly 10 to 20 percent of them would test positive for the antibiotic-resistant staph infection MRSA.

Although this fact might be scary to some, the realization is that those bacteria are virtually harmless, thanks to the immunities within a persons body. Schaffner comments that simple hygiene — showering, washing hands — "will keep the bad guys at bay."

Same goes for the barefoot march through airport security, says a Wall Street Journal report. The risk of catching athlete's foot or another fungus from fellow travelers is very low.

"It's in prolonged dampness that a toe fungus can get a foothold, so to speak," says Schaffner. "So unless you're in the middle of a monsoon and the airport has flooded, you're not going to be sloshing through a sea of water and spreading foot germs." Even in the humid month of August, when sweaty feet traipse through airport security, the area is essentially a dry environment.

Still worried? Wear socks, "not sandals or flip-flops that oblige you to go barefoot through security," he says. Should your fashion sense not permit socks, then wipe your feet with disinfecting cloths after security—"although I travel quite a bit and have never seen anyone do that," he says.

Those dirty bins—where you might set your mobile phone in the same spot a road warrior just put his smelly shoes—may carry some of the typical bacteria circulating around us, but again, the risk of infection is likely to be very low.

"There is nothing in the medical literature about catching hand, foot and mouth disease or anything else from airport security," Schaffner says.

If you're one of those people who considers wearing a face mask on long-haul flights, he adds, bring a pack of disinfecting wipes or sanitizing gel and slather some over your phone before putting it to your face. Just don't overdo it. Covering yourself in hand sanitizer and wiping down everything that comes into contact with other humans is not only impractical, it may work against you, says Schaffner.

"There is a growing body of research that says that all of us benefit from exposure to the germy world," he says.

It increases our immune system and makes us more resistant to harmful germs when they do get into the wrong place.