My GF and 3 friends worked at a telemarketing firm for a while. They said xanax abuse was rampant, to the point that people would pass out every now and then and they have to give a lecture about it. Apparently nobody gave a fuck at all, as they said people would roll blunts while on the phone and smoke them at break.
I worked in a factory (that made parallel and serial cables) one summer. Everyone I talked to was either into speed real heavy, used to be, or drank like a fish. Its extremely monotonous work. If I wasn't on amphetamine I wanted to just beat my brains out to make it all stop by the end of the day.
Fast-food places (especially sonics) are loaded with potheads. Unless you were sober when you ate there, your food probably never came into contact with a sober person. People would smoke meth and pot under the vent-a-hood over the grill, or in the walk-in freezer. Pizza places are like that too... probably many foodservice jobs. Definately waffle houses.