As far as the professional world...
From my observations, the higher up on the ladder that you go, the more you are expected to erase all signs of being feminine. Just look at like all the female politicians, there not exactly the most, "feminine" of women. It's not that they don't look like women, it's just that, the choices that they make in clothing, makeup (if they wear any other than some eyeliner), nails, shoes, etc all tend to be fairly masculine in design.
Your not going to see Mrs. Rice meeting a leader of a foreign country, with 3" heels, a knee length flowy skirt with a floral pattern, and a strappy tank with a light cardigan over it. That would just never happen. Instead, she basically ends up dressed like a man.
Perhaps thats also why certain people see french tips (or probably any type of nails that are done up beyond a neutral (read: pink) tone) as, "slutty." Especially if it's worn on a daily basis. Special occasions like parties and weddings are an exception, a long as you take it off after ;p
Hunnybun's lawyer friend was basically telling her, "If you want to be taken seriously here, as a woman, you need to look a certain way. And if you have your nails done like that (where it's obvious they are done up), it will make certain people assume things about your character. Perhaps not that she's easy, but maybe that she's not as compitant in her argument as the male laywer on the defense team. Fair? Not really. But an easy sacrifice for career success? Probably.
I just know at my job. All the low end ladies, the assistants, the frontline sales reps, low end managers, etc, all tend to look like women. I see people in heels, skirts, pretty tops, lots of makeup, lots of french tips, pretty jewelery, etc. Walk into the executive section of the building, and all you see is women in flats, and suits, nearly no makeup, conservative haircuts (nothing too long), etc. They basically look like the men who work there.