I always found hair being something that represents a person's character, but to a small degree. I am unsure about this stuff but I interpret following. Make the assumption that not styled is the equivalent of not doing anything more than making sure your hair isn't all over the place like you have been electrocuted. Also that you don't comb as intensely, just enough to get it to behave.
Short hair, or mostly tied hair (not styled) (short hair meaning from shoulder length to inbetween shoulder and armpit length) to me says that the person might have some tom-boyish traits, such as regularly participating in physical and athletic activities, and tasks that require intense concentrations (like video games). I can understand why you would want this kind of hair because when engaging in these activities, controlling the behavior of your hair tends to be distracting and disrupts your performance in these activities. But this isn't always the case as I have seen these same traits in women that wear their hair with pony tails, pigtails, or buns which share the same traits. I would also assume that they don't mind getting into fights (still stereotyping, but I want some criticism), hair pulling is a low blow. I also assume that they either have no interest in dating, or have enough male friends to the point where meeting new men isn't much of a problem, That one teeters a bit.
Long hair (not styled) : These observations are getting somewhat gradient, what I have noticed is that usually women that have longer hair but don't style it are either not interested in dating, or are already in relationships. They also hang out in an environment where they feel very comfortable or don't care about criticism about their style from others. Some Women with these kinds of hairstyles tend to be somewhat introverted and don't concentrate on social activities as much as they concentrate on other things. They also frequent social events with dominantly male attendants.
Long hair (styled): Women that style their hair to begin with like to present themselves professionally, and work in an environment where maintaining a form of professionalism is a must. These women may be intensely interested in dating or like to maintain a form of professionalism with their partner(s).
Short hair (styled): This style may also suggest that they like to conduct themselves with a form of professionalism, while also working in an environment that values integrity, punctuality, and professionalism in presentation. These women may also have interest in dating, but there is a chance that they don't often approve of people's advances because they are more concentrated on their work rather than their personal lives.