Similar to cast iron cookware, offset smokers and grills must be seasoned before use. The interior surfaces are pre-seasoned with vegetable oil before they leave the factory. This protective coating can be sticky and red in appearance. Refer to the owner’s manual for instructions on completing the seasoning process before first use. The other residue you might see, is the charcoal that has settled during cooking or food particles left on the cooking grates from prior grillings.