The difference between an act of prostitution and an act of love can't be distinguished by mere observation.
In their book Made to Stick, Dan and Chip Heath discuss the difference between motivation by consequence and identity. The state of Texas, faced with the problem of litter, figured out that 18 to 30 year-old, truck driving males were the largest offenders. The folks tasked with reducing litter nicknamed this target market "Bubba." It was obvious that Hooty the Owl or a weeping Indian wouldn't convince Bubba to stop littering. It turns out, not even a $500 fine for littering had much impact. What finally helped reduce litter by a stunning 80% was an ad campaign that showed role models (like athletes and musicians Bubba would look up to) admonishing people, "Don't Mess With Texas."
The consequences of a fine did less to change behavior than an appeal to Bubba's sense of identity, an appeal to patriotism. The Heaths go further and offer an example of firemen who were offended at the thought that they'd need prizes to induce them to attend a course that would help them to save lives. "We're firemen. Saving lives is what we do."
In this we perhaps have one of the more challenging dimensions of leadership: creating a sense of identity to which one can appeal to encourage behavior change. Leaders who know how to appeal to our better self can create so much more than those who only know how to punish our lesser selves.