When I first came to the conclusion that it is more sensible to have a shoes-off policy in one's home, I suspected that when I finally got my own place, I would not have the courage to actually ask visitors to remove their shoes. Well, I have not got my own place yet, so I have not been put to test. However, I am pretty sure that I would insist on shoes-off at the door.
I have come to realise that favoring shoes-off in homes is not just an opinion or preference, but it is a mindset. Once one comes to the conclusion that shoes are a source of dirt, then the shoe becomes abject. One developes a sense of disgust at the thought of someone wearing shoes in a home. I do not like to see my mother keeping her shoes on- it does not seem right. I cannot bear the thought of someone coming in my bedroom with their shoes on. I am pretty sure that I would ask someone other than my parents (it is their house) to take off their shoes before entering my bedroom.
This is why most Chinese or Japanese people will insist on shoes-off in their homes, even when they live in the USA or the UK. They may live in every way like Americans or British, but they find it difficult to shake off the abject association of shoes with dirt.