What does Nick learn about Jordan Baker after he has spent some time with her?

He learns that she is compulsively dishonest, and that she cheated to win her first golf tournament. She assumes that everyone else is as dishonest as she: she automatically concludes that Gatsby's books, like the better part of her own personality, exist merely for the sake of appearance.

Source(s): http://www.gradesaver.com/the-great-gatsby/study-guide/section3/