How should a teacher approach a student with distractingly strong perfume?
I might ask quietly and privately to speak to the student immediately after class. At that point, when no one else is present, I would politely say, "I am sensitive to the strength of your perfume". After that, I would let the conversation unfold. When the student would be defensive, I would just politely repeat the one statement "I am sensitive to the strength of your perfume". I might add "This is a health-related issue for me, as much as an allergy might be. It could eventually affect how I could continue to teach in the class". I would NOT ask or even suggest the student should NOT wear the perfume or take any action. I would hope the student would volunteer that step.