I think that before one decides to wear any item of clothing or footwear, they should ask themselves one very important question.
"Can I fight in this?"
If the answer is "no" then you shouldn't wear it!
A prime example of a mistake in shoe-ery is Flip Flops.
They are basically a piece of foam that make an annoying noise and remind me of the douches in college who come to class 30 minutes late wearing pajamas, and guess what else? Flip flops!
You can't fight in them, you can't run in them.. you can't even walk fast in them.
Look, I'm not a violent person. But you never know when you're going to get hassled by an old lady in the parking lot at the post office because you didn't know that she wanted the parking space that you just pulled into. After all, you're not a mind reader!
So be smart, be prepared, and just say "no" to flip flops.