Mold
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 mold 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 mold. 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.