Asian households treat shoe and feet bottoms like the devil. No shoes allowed in the house, no pointing the bottom of the soles of your feet at the Buddha, wipe your dog's paws upon entering the house. I personally wear flip flops at the gym, going swimming, etc., so that I can avoid fungal infections. I also wear house slippers. Maybe I might seem germaphobic to others, especially to those I see walk barefoot in the bathroom stalls. Sometimes my brain draws tenuous connections, like when I wonder if this dirty-feet phenomenon is why social hierarchies so easily percolate in Asian cultures. It's like a visual metaphor if you describe certain types of people as "below you" or "at the bottom [of your feet]."
But I'm trying to let it go. It shouldn't merit a disproportionate freakout if someone wear shoes into the house. The worst consequence is that the carpet gets a tad dirtier, but it's not like someone is going to die of E. coli. I have friends that wear shoes in the house, roll around and sit on the floor, and have no apparent regard for their floor being contaminated by the outside, same for their bed. I'm trying to be more comfortable with being barefoot every now and then. All as an exercise in being more flexible and letting things go.