Avoid the touts and ripoff merchants of the Djma el Fna by going into shops that only locals would use.  The people are friendly and interesting, and on one occassion I met the most excellent local man (who happened to work in the shop next door) by wandering into a herb and spice shop and saying hello to the guys chilling down the back drinking tea.  I ended up staying for ages and chatting, met all his friends later on, then was treated to a beautiful meal with his family the following night at his house.  Just at a time when I was beginning to think Morocco was full of  thieves and liars, this man and his family and friends proved how wrong I was.  Not your typical tourist experience.