It's all about proportion, centering, and alignment. http://i.imgur.com/Z5qO1.jpg
The purple circles represent the areas of discrepancy. The purple circle at the bottom right corner of her jaw, is there because her jaw is not proportional to the other side. The large black rectangle is suppose to align your pupils with your jawline. As you can see, they do not, therefore that is a discrepancy.
The medium sized black rectangle within the largest black rectangle is supposed to align the top arches of the lips to the bottom arch of the lower lip. In that area, she's fine. Then you must find the proportions of her lips. You do this by dividing her lip in half with another black line. Then you divide that newly made rectangle into two, based on the ends of her lips back to the center. In the purple circle you see there on the left side of her lips, there is an "excess" of upper lip in the lower lip. This is because to fit the golden ratio, her lips must be in a natural smile which would be the only way to not have that "excess". Therefore, that is a discrepancy.
The large green rectangle on her right eye is supposed to align the center of her eyes, to the lower center of her nose, back to the far end of her eye. As you can see in the purple circle, the end of her eye does not match up with the corner of the rectangle, therefore, is a discrepancy. There is also a smaller green rectangle within the larger green rectangle. That is a line that supposed to align the end of her nostril, to the closer corner of her eye. As you can see, it does not match up and is therefore a discrepancy. Because of this, we know that her eyes are off center and that they should be realigned to match and brought up a bit higher and more to the right.
The largest orange rectangle over the girl's iris of her left eye is supposed to align the closest corners of her eye with the ends of her iris. If you zoom in, you can see that the top right corner of that rectangle does not match up with the corner of her eyelid (without misaligning with the ends of her iris) and is therefore a discrepancy.
Lastly, the long rectangle is supposed to run through the center of the pupil to connect to the far ends of the eyelid and as you can see, the bottom left corner does not align onto the eyelid (without misaligning with the center of the pupil) and is therefore a discrepancy.
Pretty random but I thought it was cool.
TL;DR: This girl is mathematically ugly.