To dream of mold represents feelings about some area of your life having been a waste of time. Spoiled expectations. Disappointment. Wasted opportunities. Someone or something is not good enough. Feelings about something or someone being a loser worth ignoring. Feelings about wasted opportunities to be perfect.
To dream of seeing on a wall inside a room represents feelings about yourself wasting your life not doing anything different. Codes of behavior or a personality trait that is becoming an obvious waste of time. Ignoring time wasting or signals to change. Choosing to live with ruined expectations.
Example: A young girl dreamed of seeing purple . In waking life she had taking drugs for the very first time and was feeling peer pressure to take more drugs. The mold may have reflected her feelings about herself being a boring loser who wasted her life never doing anything dangerous or “cool” before she took the drugs.