Just How Bad Are Sandals for Your Feet?

Danger ranking: 5+. "The flattest, flimsiest styles of these shoes can do as much harm—if not more—as a pair of high heels," says Brenner. "Overwearing flats can cause pain in the arches and heels and can lead to bunions. There's absolutely no cushion or support, but people wear them like they're athletic sneakers. That's what makes them dangerous."

Best for: Dining alfresco; watching a play at an outdoor theater

Avoid: Museum tours; hopscotch, any kind of long walk; actual ballet

Doctor's note: If you wear ballet flats at work, stash them at your desk and commute in sneakers, suggests Brenner. Your feet will thank you.