V-stink

Not a medical concern, just a general question. Why does the Vagina and all it's discharge smell? What alters the smell and can we do something to make it smell less? Also, the film/mucus (not wet, like almost flakey?) that gathers at the lips, should we clean that away or leave it? What the heck is it? I know, it's gross. Sometimes womenhood is gross! Help a sister out?