Don't wear sandals in NYC

I can't understand why so many people would wear sandals or flip flops or slippers in NYC. I understand it's a summer wear but in NYC? It's such a filthy city, people stepping on eachother's toes all the time, rats crawling in the subways, restaurants and parks, so much trash everywhere and ewww the smell of trash in the middle of the baking summer sun.. trash is cooking real high on the nose!

I don't know, I just cant bring myself to wear sandals and if I have to, I'll end up wearing socks but I don't, I just wear my tennis shoes. I rather do that than catch some disease from the filthy streets of NY.