If anyone has been around her for awhile they realize she does it and just learn to ignore her.
I used to date a girl who was basically honest but when she did lie, was so good at it that even knowing for certain she was lying, I found myself believing her.
I don't know which is worse.
Within the last several months I realized a person I had considered a friend was a pathological liar. I hadn't realized it because I didn't hang around with this person a lot until a few months ago, and I didn't really want to see the faults of this person, in order to maintain the friendship.
Pathological liars need to be avoided like a serious illness. They are destructive like poison. I learned a valuable lesson, albeit the hard way.