Because Mingzong killed the ancestors of the Qing emperor, and the ancestors of Manchu were also slaughtered by Mingzong, Mingzong certainly could not be recognized as a wise king by the world. In addition, during his reign, he appointed eunuchs at will, which led to chaos and disaster in Wan Guifei. During his reign, he basically didn't do anything conducive to the failure of state affairs, so Ming Xianzong was a bad king.

Moreover, when I first became emperor, the Jurchen tribe became stronger and stronger, and even began to harass the border people of the Ming Dynasty and defeated the Ming army many times. The purpose of the Jurchen tribe is because their tribe's productivity is low and they need to plunder property to meet their own needs. But at that time, Ming Xianzong knew that this was not a matter of appeasement, but a direct order of genocide, just for his own sake.

It is because of his practice that the rise of Jurchen has been pushed back for more than a hundred years. And at that time, Ming Xianzong should know the purpose of Nuzhen before making a decision, but Ming Xianzong was too anxious to bully people, so he made such a decision, which not only made Nuzhen almost suffer from the crisis of genocide, but he also had other ways to solve it, but he didn't.

Moreover, in the political affairs, he is also a person who cares nothing, so future generations will call him a bad king. In fact, if he had adopted a more moderate policy at that time, it is estimated that the result would not be as it is now, and there would be no title of a bad king, so it is mainly because Ming Xianzong is too cruel to do things.