Well, not so much about flip-flops as about how people walk in them. You see, I am of the firm belief that flip-flops derive their name from the sound they are supposed to make when you walk, "flip...flop...flip...flop." The sandals are not called shufflers, draggers, or chtchtchts.
A typical pair of flip-flops. Cute, right?
So as warm weather is upon us, and people stroll around in their comfortable summer sandals, why is it that all of the sudden nobody knows how to lift up their feet anymore? Why do so many people become foot dragging apes, just because they are wearing flip-flops?
PICK UP YOUR FEET!! PICK THEM UP!! DON'T DRAG THEM! YOU'RE DRIVING ME CRAZY! I WANT TO SCRATCH MY EARS OUT JUST HEARING YOU DRAG YOUR LAZY BEAST FEET!!!! PICK THEM UP!!!
(take a deep breath Gordita)
There are a few groups of people who are exempt from the "pick up your darn feet" rule: the elderly and people with physical disabilities (laziness is not a disability). Also, if the ground is covered with a sheet of ice, I would suggest dragging your feet so as not to slip. So, to sum up, there are two groups of people and one situation I can think of in which it is acceptable (in my humble, but ludicrously strong opinion) to drag one's feet.
You can be assured that if you are walking behind me, dragging your feet, I will stop to look at "something really interesting" to let you pass so I don't have to hear your gorilla feet drag on the ground. Or, if I'm feeling really immature (which happens to be extremely rare *cough*), I will imitate you obnoxiously so you will have a live demonstration of just how annoying you are, unless you don't get the fact that I'm imitating you on purpose and just think I'm annoying for dragging my gorilla feet.