Why do some people's female genitalia smell worse than others?

Multiple causes: It could be infection, it could be hygiene issues, it could be a lack of fresh dry air to the vaginal area. Vaginal ph (acid level) may also effect the odor slightly. Recent unprotected sex will also cause an odor. I recommend no underwear to bed when not on your period, shower over tub, cotton panties over thongs and non cotton, and wiping front to back as a start. See you gyn if odor is new.