Dr. Rappaccini is an ambitious doctor who seems to care a great deal more about his research than he does about people. Dr. Baglioni's claim that Rappaccini would gladly sacrifice a human life in order to add to his research and knowledge is confirmed by his daughter's poisonous existence as well as Rappaccini's involvement in converting the protagonist, Giovanni, into a poisonous person who can serve as a companion to his daughter. Rappaccini has sacrificed any possibility of his daughter's having a normal life, raising her alongside a poisonous plant she cares for and refers to as her "sister."
Rappaccini also ruthlessly, and without care for Giovanni's feelings, makes him the subject of an experiment, as he did his daughter, and removes the possibility that Giovanni could live a normal life. He has alienated his colleagues and peers, so much so that Baglioni is anxious to exact his revenge on Rappaccini. To be fair, he does seem to love his daughter, Beatrice, since he entraps Giovanni in order to make her happy, but he is not ultimately a good judge of Giovanni's character; Giovanni speaks so harshly to Beatrice once he realizes that he has become poisonous as well that he renders her willing to take her own life rather than live with his suspicions.