It is true that crazy or nightmarish dreams help create lucidity. The dream scenario can be so horrifying or bizarre that you question reality itself, making you come to the conclusion that you are in a dream. You probably get lucid in calm dreams because in waking reality you probably practice your awareness/reality checks during your calm, down time. And yes, it is very possible to incubate a dream to increase lucidity. It is called the VILD(Visually Incubated Lucid Dream) technique.