Readers can learn all kinds of things from Lady Macbeth, and most of those things are probably not "good" things. We can learn that lust for power and fame can corrupt a person and motivate them to do things that are completely amoral. Once Lady Macbeth learns of the prophecy and the real possibility that her husband can be king, she sees the very real possibility that she could be queen. It is at this point that she decides that the end justifies the means, and she gets what she wants. There is a lesson there for people about doing whatever it takes to get what you want. I do not think Lady Macbeth is a positive example of this concept, but readers are definitely learning about it. Readers can also learn that bullying is an effective means of getting what you want. Lady Macbeth wants to be queen, and her husband decides that murder is a cost that he is not willing to pay. Lady Macbeth's response is to verbally abuse and bully her husband into action, and it works. Again, this is not a lesson that I want my daughter to learn, but it has to be stated that the lesson is there. Finally, Lady Macbeth does show readers that guilt is real and quite powerful. Her guilt ultimately destroys her on a mental and emotional level, and it even effects her physical health through sleep deprivation.