Dreaming of being dumb is an ominous sign indicating that someone is watching you and intends to hurt you.
Dreaming of being dumb in a sudden and speechless (when you tried to speak) suggests that there may be villains speaking ill of you but you can not find the reason and will fall into difficulties.
Dreaming of being dumb for a while and then resumed normal indicates that you will ultimately defeat the villain.
Zhougong’s Dream Dictionary
In the Chinese culture, dream is linked with a virtual person called Zhougong after a popular book Zhougong’s Dream Dictionary (周公解梦) which has been passed down from thousands of years ago. The book categorizes seven types of dream that people usually have during sleeping. With thousand of years’ history, Zhougong’s Dream Dictionary (周公解梦) has been popular in China as well as in the Chinese communities for its excellence in explaining different dreams, in particular those unusual and weird. While some believe that the book shows people’s superstition, others believe that the objects or scenes that show up in our dream have close relationship with what have happened within our body (e.g. health status), in daily life, or mental status.