Like Death or experienced witches, Susan can make herself completely unnoticeable to ordinary people if she so chooses, though anyone who "can see what's really there", such as Albert or Mustrum Ridcully, who are used to such things, are still able to see her if they concentrate and she is not actively trying to avoid their specific notice. During her time at Quirm College, she unconsciously used this power to avoid being asked questions in subjects in which she had no interest, such as Literature and History. Unfortunately, this caused the teachers of these subjects to believe that Susan was not attending their classes, and she was reported to the headmistress on several occasions. She solved this problem by using her power to erase the headmistress' memory of her supposed misconduct.