One of my pet peeves that drives me absolutely nuts is someone walking in the house with their shoes on. I cringe and I can feel the stress building up every time some one walks into the house and doesn't remove their shoes at the door. Not only do shoes drag in so much dirt and mud, they are just so dirty and full of germs. Think about it, you walk out in the streets, sidewalks, parking lots and so on. You are stepping on where someone has spit and it has dried on the sidewalk, where people spit their gum, a dog has probably taken a pee where you have stepped and so much more. Then you walk into a house and drag all those germs all over the floor. When your having a barbecue or a party, it is understandable there is going to be a lot of people walking in and out with their shoes on. But, when your just walking into someone's house or apartment, please remove your shoes.
I am one of those people who has to mop when I know someone has walked through the house with their shoes on. Usually not right away, but I will mop the floors the next day. You would be surprised how dirty floors get from someone walking in a house with shoes on.