One aspect that is probably being confounded here is that hair plays a huge role in attractiveness. By putting on a hijab and hiding her hair this girls attractiveness (at least by western standards) probably went down a bunch of points. So part of what she may have just experienced is what it's like to be an uglier person.

An interesting experiment to come up with would be to wear something that clearly indicates you are muslim but doesn't change your physical attractiveness (again by western standards).