Why does having a “good” and “bad” death so important and what is the difference?

Having a good death is that it was peaceful and not painful. For example, someone passing away in there sleep. 

bad death, meaning something that is a little more tragic. Like a horrible accident or murder. 

Having a good death is the way you'd hope you die, in the least painful and most comforting way possible and having a bad death is the like the last way you'd want to die, like being set on fire. Those are the differences whatever way of dying seems more peaceful to you versus the worst.