Appeal to Emotion? Bad? Good?

Appealing to emotion in a descriptive conclusion that cannot be deleted or changed designates a bad argument. For example, "I know I deserve to eat this cake. Today I only ate the healthiest thing on the McDonald's menu. And my diet has been going well so far. It won't hurt anyone and I really deserve this cake all to myself." This situation is also called wishful thinking. We often talk ourselves into thinking about a decision in our own little world. Just because we want something doesn't make an argument valid with our own appeals by emotions. Appealing to emotion in a prescriptive conclusion can be either good or bad. For prescriptive arguments, we are able to change it from bad to good based on how we use emotion to enhance the argument. The book also mentions that we should start to use appeals to emotion as an indicator as whether or not the argument is bad.