Why is this experiment causing Charlie to have many feelings of naughtiness and anger?

As Charlie gains intelligence, he begins to understand that he has been used as no more than lab animal by Dr. Nemur and Dr. Strauss. His well-being is less important to the scientists conducting the experiment on him than the experiment itself. He realizes that he is, therefore, no different than the lab mouse Algernon. This makes him angry. It also makes him angry when he discovers the scientists, especially the ambitious Dr. Nemur, probably rushed in too quickly with the brain surgery.
Finally, Charlie becomes angry as he realizes that the experiment has failed, and he will become mentally handicapped again. I wouldn't say he is being "naughty," but this situation causes him to act out angrily at the people around him. He is frustrated and upset, as any person would be in a similar situation.