This is something I've always asked myself: why do we find our own natural scent as a species so repulsive? I mean, think of all the completely unnatural hygienic routines we have to undergo each and every day just to not offend other people with our various odors. It seems like there is a logic to why things usually smell "bad": - a rotten apple smells bad to us, because it would cause us to be ill, so finding that apple's smell repulsive is a helpful trait we've evolved - poo smells bad, because it also poses various health risks, and it's helpful to feel the need to stay as far away from it as possible (flies have evolved to find that same smell attractive) So, I can understand why the smell of extreme filth on a human would be unattractive: rotten teeth, extreme body odor, etc. would all indicate poor health (possible infection, disease, or unwanted traits for offspring); but it seems to me we have evolved to be irrationally sensitive to bodily odors— For example, if I were to meet a girl that just went a week without showering and brushing her teeth, even though there is nothing technically wrong with her and logically I should find her just as appealing (ie: neglecting one's hygiene for a few days is not likely to pose a health threat... hell, even doing so for a month wouldn't; we've survived as a species for thousands of years of not showering and brushing our teeth every day*), I would still find her completely unattractive, even repulsive; even if she was incredibly attractive physically, my repulsion to the odor of someone who has neglected their hygiene for just a week (ie: the natural odor of a member of my own species) would overpower any other attractive qualities she may have. I'm not even sure if this qualifies as a question. Maybe it's just a general observation. * did people in the middle ages open-mouth kiss? because they never brushed their teeth then. gross.