Some people find it hard to take a proper bath daily. Some people can go for days before they even have one. I remember a fellow student in my secondary school saying that he doesn't like taking his bath because he didn't want to fade off just as clothes fade off when people wash them.
You would be thinking that nobody has done it before for a long time, then check again because Kailash Singh and Amou Haji have been able to intentionally not bathe for years. Mr. Singh as of 2011 hadn't had his bath for 37 years because a priest guaranteed him of having a son and heir if he followed the advice of not taking his bath. Actually, he has 7 daughters already and he is yet to have a son (I understand that he is a man of faith just like Abraham but a man of smell is another level). Amou Haji on the other hand didn't have his bath for almost a century because he was scared of falling ill as a result of bathing. He actually died in 2022 but trust me when I say he died with the award of the world's smelliest man.
So what would actually happen to us if we do not bathe for a long time, I do not mean for a few days, I mean for a very long time. First, we would expect to see the person have an awful body odor coming out. You start to perceive this smell even before others, and if you do not correct the wrong, you will begin to ooze this odor which would catch other people's attention. The smell will start from areas with hair such as the armpit, the pubic regions, the hair on the head, and between toes and fingers and this is because bacteria on our skin come in contact with sweat.
Over time, dead skin cells, and acne would begin to build up on the skin since they are not being washed off regularly. If this continues for a long period of time, it would lead to hyperkeratosis where there is the thickening of the stratum corneum, which is the outer layer of the skin as a result of keratin buildup on the skin which can be accompanied by skin rashes.
While the body would be looking really messy with skin fungus finding their way to the skin as well as colonies of bacteria because we are sure that they would since it would be an impressive breeding point, cuts such as wounds would be prone to infections easily. While bathing does a lot, and disinfectant companies even show that washing the hand regularly would help fight bacteria, a journal from the Centers for Disease Control and Prevention says that bathing has aesthetic and stress-relieving benefits but serves little microbiological purpose.
David Whitlock, a Chemical engineer did a study on horses and how they use colonies of bacteria to keep their body. He decided to culture ammonia-oxidizing bacteria which would help to salvage body odor in the skin without using soap as it consumes the byproduct of the bacteria and although he didn't discourage people from taking baths, I guess the ammonia-oxidizing bacteria spray can replace body sprays.
While not showering is completely bad, showering too excessively is also not good for you because the body produces normal microbiomes which serve as protection from outside infection. Remember that not bathing for a long time could lead to rashes, acne, and terrible body odor, skin fungi are going to be a part of your outer body. Your scalp and head hair would not be left out as you would have to fight with dead skin, dandruffs, and other hair to scalp infection. One more thing, onw day of bathing after a long period of not bathing would not make your body go back to normal. Also, if you think probiotic spray will help you grow body microbiome then think twice because according to Dr Mahto, there is no evidence that dead probiotics applied to skin will encourage 'good' bacteria. So if you are thinking of doing a no bathing challenge, then you should think twice.