Lo-Fi Games

Step 1: You enter a shop, fight guard and shop owner, loot everything and your reputation with this faction is negative.
Step 2: You heal the guard and shop owner before they die and your reputation is now more positive than before step 1

Seem fair

This works even better for diplomatic characters. Already have -100 with a faction? Beat up a diplomat and then heal him/her. Much cheaper than buying your way out at a pacifier.