I suspect that your floors are a lot less hygienic than the inside of a pair of slippers that have briefly been worn by someone else.
Personally I can’t stand begin barefoot in almost any situation, & don’t see the point of cleaning floors with my socks. I have two levels of indoor shoes; actual slippers & a pair of slip on trainers which are also OK for nipping outside on paving & decking if it’s dry.
Most guests enter our house into the large kitchen/salle de séjour, which has a tiled floor so I never ask anyone to remove their shoes unless they are clearly muddy, but most people would have removed them anyway if that were the case.
Was their home carpeted? I have cleanedmany a carpet commercially and the dirt that comes out of a carpet is incredible. A pair of slippers would be much cleaner internally than the carpets in most places I would expect. Outdoor shoes on carpets?
One of the reasons I really like the (rural?) French tradition of hard floors – at least downstairs – is that they are easy to clean and I don’t have to take shoes off. My partner never takes shoes off anyway but the only part of the house that is carpeted is around the guest suite so it really doesn’t matter.
We only have one set of friends who require the shoes-off approach and after a couple of experiences with slipping on their shiny floors, we now take slippers. When they come to us, they start taking their shoes off and we ask them not to. Our floors are never clean enough to avoid embarrassment given all our tooings and froings
At that time (early 1980s) pretty much everyone had carpeted floors (I recall there was even a brand of carpets for kitchens) so yes, however this was greater London, so we all walked on pavements rather than through mud. We had carpet in our livingroom in Oxfordshire until the flood in 2020 and wore outside shoes on it. We also had cats that would go out and come in without wiping their feet.
I can see why some might not want to wear other people’s slippers, which are a much more enclosed environment that can retain sweat and odours that a hard floor would not in the same way.
artificially aged, though?