It's hard to tell what does it exactly. Maybe it's the tendency of good guys to have larger Johnsons than their evil counterparts. Perhaps it's the realization that Good People Have Good Sex. But for some reason or other, sending an evil woman to seduce a hero has a surprisingly high turnover rate. There's a very good chance that's she'll just decide to bat for the other team (moral team, that is) rather than stick to the original plan. The sexier the hero, the more likely this will work. For a darker relative, see Rape Is Redemption. Related to Sex Is Good. Examples of Sex Face Turn include: