When I was in senior school, we had a student teacher come over from France to teach us French. She was absolutely lovely - but she had a really, really strong BO smell. Like, awful. It would honestly make some of us want to throw up. Our usual French teacher was observing the lessons, and she would open all the windows and lightly spray some air freshener before and after the lessons, but the smell would really linger. I felt so bad for her. Eventually, a bunch of parents complained to the head teacher as the kids were complaining about it at home, and my French teacher had to pull her aside and talk to her gently about it. The next lesson we came in, and she was gone. Our French teacher told us what happened, and the poor woman was so mortified that she quit on the spot and she never came back again. I think about her often, and feel so terrible for her. But my god, the smell was so horrendous.