What is a possible consequence of painting on unsanded surfaces?

Painting on unsanded surfaces can lead to peeling or blistering paint because the rough texture of an unsanded surface does not provide a proper grip for the paint. When paint is applied to an unprepared surface, it tends not to adhere well, which can cause it to lift away from the surface over time. This poor adhesion can be exacerbated by environmental factors like humidity or temperature changes, leading to further issues such as peeling or blistering. Proper surface preparation, including sanding, is essential for ensuring that paint adheres well and provides a durable finish, thereby preventing such undesirable consequences.