Hygiene is not health
Being clean for the sake of being clean is a dubious luxury or social expectation but not a physical necessity
There is something really off between the British Protestant men who insist on wearing closed unventilated shoes all the time year round in a very damp or humid climate and the Catholic foot-washing practices for women which perversely involve obligatory pedicures with nail polish. There are far too many doctors of a pernicious “public health” bent with a nasty focus on foot fetishes, adulterous footsie games and religious practices of footwashing.
If public health doctors want to offer sex shots or STD clinics, then that’s what they’re offering but don’t start off with a footwashing or try to extort a religious confession if sex really is the goal of all the labor-union local government-mandated and enforced public health doctoring. “Public health” is completely amoral and far too brutal for small children, between the abortions provided and the government mandated vaccinations with dirty needles, with all the other routine mayhem as so often performed on a cheap and practical veterinary basis of managing human populations as cattle.

Walking barefoot in the sand or dirt is or with dirty feet in sandals is not at all unhealthy. Mud or sand or water to wade in is all about convenience, and shower or bath is solely for etiquette around other people at “clean” or formal indoor social functions. People can be dirty and smelly for months or years on end and take a shower or bath and wash all their clothes all in one evening and be clean. So it's little or nothing to do with “habits” either. Situations and circumstances only.
Neither working outdoors nor being stinky, sweaty and dirty in general injures human health in the slightest. The important thing about feet is their ability to quickly transport a person elsewhere if another person is inordinately concerned about them.