I realize some people won't talk to you if they see that you are wearing flip flops because they HATE them. However, there are a lot of people that love flip flops and practically live in them from March to November. According to Health.com, there are a few times that you should not be wearing flip-flops.
1. Don't walk your dog in flip-flops. A study in 2009 found 18,000 different types of bacteria on one pair of flip-flops, including fecal matter. Eww!