Our experience might be a little different than most because we elected to tour the endless stalls of the Medina with a local guide--a tip I'd recommend if you want to get an overview of the area before venturing off on your own.
The Medina is a very confusing maze where you can purchase everything from jewelery to olives and lamps. Our guide gave us prices we should pay and found that nearly everything we inquired about was 3-4x more expensive. Beautiful and elaborate caftans, for instance, were being sold for $80-100 here. While in Ville Nouvelle (new town, just 5-10 minutes outside the Medina), these could be purchased for about $20-25.
We didn't experience aggressive sales tactics and even though I was wearing a sundress, I didn't feel I was getting unwelcome attention. In general, I'd say 75% of Western female tourists wore shorts and tank tops (if not less) and it didn't really turn heads.