You send the pretty gals and handsome guys — not the dumpy nerds. That’s basic marketing. You want your product to have good associations.
When does it cross over into the unethical? Obviously it can, whether or not it did so in this case. There’s a reason that prescription drugs are also called ethical drugs. Being too free and loose can invite trouble. Being too tight can be cruel. Pro-active coaching of patients would seem to be the best middle road, along with small initial supplies and close evaluation of the patient.
Translation: Sex Sells! :>)