Sue is right. The term started in the magic profession.
Today the term also encompasses all things that appear one way and are really something else. For example, "Stu might seem like a big success, but it's all smoke and mirrors." In other words, Stu looks successful, but that is just an illusion.
The "Great Smoking Mirror" teaching originated from the native people of America.The Cheyenne,Pawnee and Mayan tribes used the great smoking mirror philosophy which means:-"I am another one of yourself ".
Which roughly translates as within ourselves are the traits of others and vice-versa. When we really search past the smoke of our personality do we find the true self.
I think BrendaEvans put it another way but the meaning is basically the same.
Hope this helps.