Macbeth killed the king, which was soon general knowledge, and had had Banquo and Macduff's family murdered. They had gone against religious and moral dictation, and had decided to live outside of the rules, as it were. But these actions were not without consequence for Macbeth and Lady Macbeth. Their characters were far more complex than the other characters could tell.
It is the audience who can see the full detail of these two characters. From the asides and spoken thoughts from the two we gain an insight not given to the other characters. This complies with the theme of deception; at the beginning, it is that Macbeth is plotting to kill the king when putting on a happy face, then the two, Macbeth and Lady Macbeth pretending that they know nothing of the murders and covering up their little mistakes. Later it is Lady Macbeth hiding her fears from Macbeth and Macbeth killing Banquo without his wife's consent. .
From then on it seems that we no longer see the harsher sides of the two, as Lady Macbeth begins to crack and Macbeth is openly violent, but instead we see the sides of their old open' characters, that is the characters that the other people saw. We begin to understand more about Macbeth, how he has begun to lose fear and begins to feel the stress and repercussions of his actions, and Lady Macbeth shows that her cool calm exterior is just a fazade.
The signs to show that Malcolm's statement is not wholly true are clear again to the audience. To begin with, Macbeth does not leap at the chance to kill Duncan and seize his throne. Instead he deliberates, and decides that it would possibly be best for chance to crown him without his stir'. This shows that Macbeth ahs already fought against his conscience and lost. It shows us that he does indeed have a good side, one who does not wish to kill, to go against religion and morality. This proves that he was not just a butcher'. Also, it seems to have been mainly the witches' fault for stirring in Macbeth visions of power above his station.