The flip-flop is more dangerous than you might think. Researchers say a film of grime that coats your feet at the end of a day of flopping around town is some dangerous dirt. Lab tests of two flip-flop fans, worn for four days, revealed a potentially deadly germ (Staphylococcus aureus) lurking on the rubber. If it seeps into a cut on your foot the bacteria can enter the bloodstream and, if left untreated, kill you.
… Tests on just one pair of the flip-flips showed they harbored approximately 18,100 bacteria of the five most prevalent varieties found. And that’s what accumulated in just four days.