Mould or mouldiness in dreams suggests that the essential energy has dissipated. There is no longer a link to the spiritual dimension.
Psychological / emotional perspective: When in dreams something has gone mouldy or has putrefied, it has been contaminated. Emotionally there is a negativity present, which indicates that we can no longer appreciate a sense of clarity; our vision is clouded and has upset our balance.
Material aspects: There is a sense that the life has gone out of a project or task, perhaps that in waking life they have gone on too long or lost focus. If, in dreams, food has gone mouldy we no longer have some essential support.
If mould is growing, for instance on a wall, there is a negative energy around, which suggests there may be difficult times ahead if it is not dealt with properly.