By Peter Funt

Say this much for Donald Trump and his most rabid defenders: they have a way with words. Mostly, however, it’s the way of Madison Avenue.

The best marketing campaigns don’t try to change behavior or create a need where none exists. Rather, the goal is to magnify an underlying concern and turn it into a sales pitch. 

So, for example, because Americans worry that most fast food is junk food, Subway tells them to “Eat fresh.” Since so many people struggle to kee...