I think the core value of all hipsters is individuality.
For the duration of this answer, I am defining a “Fake Hipster” as someone who wants to look like a hipster, an “Obnoxious Hipster” as someone who strives to emphasize their individuality and a “True Hipster” as someone who is unafraid of their individuality.
Fake Hipsters
Like most fake things, Fake Hipsters are very easy to spot. While anytime before 2005ish, the styles listed in the above answers could have described a small group of True Hipsters – for some time these represent a basically passe dominant alternative culture trend. Fake Hipsters are more sad than obnoxious because they come from a place of insecurity and desperately want to be seen as cool.
Obnoxious Hipsters
These people prize their individuality and are generally arrogant about exactly how individual they are. The irony of course is that the desire to be unique is not unique – explaining the denial of being labeled as a hipster, god forbid they be put in a group of other people just like them.
This is why they don’t want anyone else to like their bands. This is why they are uninterested in anything popular – unless it so bad that no one hip likes it and they can like it in a unique, ironic way.
One of the fundamental rules of sociologly is that the only thing that can be truly unique is combinations – so a hipster usually tries to establish a breadth of interests that don’t usually reside in one person. This carries over to fashion, too – the idea of unique combinations. It is one thing to wear a sex kitten dress from the ‘90s, but wear it with a beige WASPy Liz Claiborne silk knee length walking jacket and win the sartorial awe of your Obnoxious Hipster colleagues.
Obnoxious Hipsters really want you to know how individual they are – so fashion matters a lot to them. While their sartorial choices can be fresh and exciting, as opposed to the derrivitave Urban Outfitter tastes of the Fake Hipster, they are also generally over the top.
With an open mind and taste, the two virtues of an Obnoxious Hipster, and aversions to the popular and the difficult, the two downfalls of the Obnoxious Hipster, it is easy to develop esoteric interests. Being interested in interesting things makes you interesting – and being interesting takes you very far in a society that is based on and strongly rewards individualism.
True Hipsters
Stylistically it is hard to pinpoint a true hipster. They might still part their hair to the side because they thought it looked awesome, they might not. Generally, they go on with their interests regardless of what people will think of them. They don’t really try to be interesting – they just are interesting. They don’t care if you call them a hipster or if you like Lost, too. They are nice, confident and not easily threatened. Because most modern hipsters are atheists plagued with apathy – they don’t care what you think of them, they don’t really care about much of anything! They don’t think much matters – so they run away from boredom with either hedonism, workaholism or a postmodern assortment of distractions and interests. Some have figured out a way to monetize their interests – either as a tastemaker or bettering one of their esoteric interests.
Or not. A lot of people are sometimes True Hipsters and sometimes Obnoxious Hipsters.
I’m not sure I can fully intellectualize the might of the True Hipster, but I can say they are far and few between and have a bright, big fearlessness that is magnetic.