What does the blind girl not "see" about the Tramp? What does she not realize about the tramp due to her blindness?

When she first meets the Tramp, she is blind and since she cannot see him, she assumes this is the millionaire she has been dreaming of. Everything that happens in their relationship from this point on just falls in line with the girl's dreams. The Tramps buys a flower for her and leaves in a limousine (the way she sees it). The next time she meets up with him, he buys all her flowers and takes her home in his limousine. The Tramp comes to visit her when she is ill and learns of her overdue rent. He also reads her the newspaper ad that introduces the idea of the girl having her sight restored. He returns the next morning and gives her money for the rent and money to have the eye surgery. They do not meet again until the Tramp is released from prison and the girl has had her sight restored.

The blind girl is young and naïve. She expects to meet a millionaire to love her and take care of all her needs and wants, and this is certainly the typical thoughts of a beautiful, youthful woman in the 1930's, when the film was made. Since this vision of a handsome millionaire occupies her thoughts, that is what she assumes she has found in the Tramp.

Once her sight is restored and she watches the Tramp chase after the newspaper boys, she teams with the boys in making fun of him and his plight in life, particularly when he sees her in the store window, smiles and her, and she turns to her grandmother to tell her she has an admirer.

However, her goodness takes over and she calls to him before he is out of the range of the shop. She hands him a fresh flower and a coin, and when she discovers that this is the "millionaire" she has been dreaming of and whose return she has been anticipating, she must sort through a range of emotions. She finally accepts him for who he is, as evidenced by the final expression on her face.