In answering this question, we will break down two of Jordan Baker's most important characteristics and use examples from the book that illustrate them.
The first of Jordan's characteristics that we're going to look at is her extraordinary dishonesty. Jordan may be very alluring on a physical level, and she may be an incredibly charismatic young lady to whom men are irresistibly drawn, but she's also flagrantly dishonest—not just once or twice, but on a regular basis. It's no exaggeration to say that Jordan's dishonesty is pathological.
A prime example of this comes in the revelation that Jordan, a golfer, cheated to win her first tournament. Once we learn this about her, we're immediately placed on guard. There's something pretty unpleasant about a cheat—something that indicates that we're dealing with someone for whom the rules mean nothing.
Our initial suspicions are confirmed when Nick observes how Jordan routinely twists the truth to keep herself at one remove from a world which, as she knows full well, can be a very harsh and cruel place. Jordan's lies and dishonesty may have a lot of history behind them, and they may constitute a mask of self-protection necessary to survive among the well-heeled East Egg crowd, but that doesn't change the fact that Jordan is a fundamentally dishonest woman who simply can't be trusted.
In addition to her serial dishonesty, Jordan is somewhat aloof. When Nick sees her for the first time, she's stretched out full-length across a couch, holding her head high in the air as if “she were balancing something on it which was quite likely to fall.”
There is something quite revealing about Jordan's statuesque posture. It's as if she regards everyone else as somehow beneath her and believes that it's almost a privilege for them to be in her presence. Jordan's aloofness is intimately related to her dishonesty. As she regards herself as high above everyone else, she doesn't feel constrained by what she regards as their petty little rules and regulations, whether it comes to telling the truth or playing golf.