Watermelon's bad dreams may be related to their living conditions, emotions or problems. Simply put, rotten watermelons may imply some negative changes or losses.
From the numerology point of view, watermelon represents wealth and fortune. Decadence means the loss of wealth or the decline of fortune. This dream interpretation may imply economic losses or some difficulties and setbacks in life.
However, dream interpretation is a subjective knowledge, and everyone's dreams and their meanings may vary from person to person. Therefore, I can't accurately explain your specific dream. If you want to know more about your dreams, I suggest you consult a professional dream interpreter, who can interpret and analyze your dreams more accurately.