When they get gunked up, I'll soak overnite in a degreaser like simple green.
Rinse and bang them on the side of a bowl and rinse again.
They usually come out almost new again.
Looks good butt marinades only penetrate 1/4" or so. Fine for thin things like steak, chops or chicken.
Too much mass for a marinade to work on a butt IMO.
Was it injected or brined at all, could you taste it all the way or just on the bark?