Gutting the creature yields 20% more creature products.
By activating this Charm on a creature your chances of looting the Creature Products the creature drops are increased by 20%. Because the bonus is not very high it's debatable whether this Charm is worth its extremely high price or not. Even if the objective is to loot some expensive Creature Products dropped by weak creatures (that wouldn't require any other charm), it is probably still more beneficial to simply hunt something else that drops good loot instead using the Offensive or Defensive charms. Therefore, it's not recommended to buy this charm unless you have already obtained the most useful Offensive and Defensive ones.
With the Summer Update 2020, this charm effect was changed from 10% to 20% and its cost was decreased from 2000 to 800 charm points.