It would be interesting to see an Ophelia flummoxed by “Are you fair?” like the way it might be confusing for anyone to be asked, “Are you beautiful?” Especially someone who was looking right at you.
If you say “yes” you’re vain. If you say “no,” you’re lacking confidence. It’s a trap question. It’s unanswerable. The only appropriate answer to this is a question that questions the premise of the question.