From a reader:
Years ago in Time magazine – I think – there was an article about two guys who would help potty train your kid for a fee. They used cookies and candy as a reward. A letter writer to Time complained that giving treats as a reward sent the wrong nutritional message. Instead, the person wrote, these two entrepreneurs should have been rewarding the kids with carrots and celery sticks.
I suspect that the letter writer’s offspring were still using diapers into adulthood.