This always really bothers me when I see it on mumsnet.
We are a "no shoes in the house" house. I have a two year old and a 5 month old who are on the floor but even before we had them we didn't allow shoes in the house, I grew up in a house that was no shoes.
I can't get over how people don't "get it"!! The street is filthy, there is literally urine, faecal matter, saliva, engine oil, bird excrement, food waste, vomit, general grime etc EVERYWHERE. The germs are countless. I cannot believe people don't care about all that being trodden into their houses, on their carpets, into their bedrooms etc.
Having children makes this even more unbelievable for me. I don't wrap my kids up in cotton wool and helicopter parent but I do take precautions to ensure that they are as safe as possible and the house is as clean as possible for them.
Some people don't get it because we have a dog - they don't realise that the dog is only allowed in the kitchen, the lounge and the conservatory. Not the playroom or upstairs at all, ever. Even then, the dog goes out to the conservatory after coming in to dry his feet/get rid of detritus before coming into the lounge/kitchen.