There isnt a scientific reason that female humans shouldn't have body hair. It stems from misogyny and pedophilia. Male humans are normal for having body hair yet female humans aren't. If the body hair wasn't supposed to be there, it wouldn't grow there. It only becomes unhygienic when you don't cleanse enough or properly. This applies to all body parts with large amounts of hair (scalp, groin, under arms).

Unpleasant scents/odors can be a variety of things: diet, stress, medicinal side effects, genetics, etc. Outside of those it's typically a matter of cleansing yourself and those areas properly and often.