The worst memory of my hair styling career was having to tell a little girl and her mother that I suspected the little girl had lice and I couldn't cut her hair. (cosmetologists are only qualified to say they "suspect" a condition, and then refer them to a physician.)
Poor thing was so infested, nits all throughout her entire head of hair, she started crying, it was so awful. I am tearing up right now just remembering...
I bet that incidence was a childhood trauma for that little girl.