"the two weeks worth of hair growth under her arms suggests to me that she probably had a substance abuse problem which prevented her from taking care of basic hygiene at the end of her days."
Umm...I'm female and have no substance abuse problems, but I haven't shaved my armpits for weeks. Not all women consider shaving their armpits a matter of "basic hygiene." You are less likely to shave your armpits if it's not summer and you're not wearing sleeveless tops, if you think that the idea that women MUST shave their armpits is old-fashioned, if you don't have a lover, if your armpit hair is sparse to begin with, or if you come from one of the numerous countries where unshaven women are common. Come to think of it, maybe the Mount Vernon Jane Doe was not American? That might explain the unibrow as well, and would be a plausible explanation why no one has been able to identify this lovely young girl. This case has haunted me for years, ever since I first saw the post mortem photos...