I think that most of the characters in the play are deceived by Hamlet's act of being crazy and he uses this belief to his advantage to truly look at who the people around him were. Gertrude certainly thought her son was nuts when he was talking to the ghost in her bed chamber. While in the bed chamber Hamlet was deceived by his ears when he heard the rat behind the arras thinking it was Claudius and accidentally murdered Polonius. I think Hamlet really loved Ophelia, but she was deceived by her ears when he told her all manner of hateful things to throw off his adversaries. Claudius deceived everyone's ears trying to cast suspicion elsewhere from his own murderous plot to rise to the rank of king. R & G attempted to deceive Hamlet's eyes and ears by pretending to be his friend in order to gather information for the new king. Claudius and Gertrude deceived R & G's ears by paying them inflated compliments in order to get them to be spies. The poisoned wine and sword tip were also deceitful because they appeared normal, but were actually lethal several times over.