A guy I know asks for guacamole, and then lettuce on top of his bowls. They usually don't see the guac through the lettuce. I actually accomplished this by accident once, but i don't feel so bad because the guac is the ONLY overpriced thing at the place.
Also, you haters of these chipotle/qdoba type places are fools. I'm glad you have 4000 mexican restaurants within 18 feet of where you live that all give out free food all day. For me, 7 bucks for freshly assembled, clean, non greasy combinations of meat and veggies that doesn't require any wait or waiter service is a great deal.
Yes, jose's tacos down the alley way in the ghetto does offer great tasting authentic food for cheap... but sometimes I just want a damn qdoba gumbo or chipotle bowl.