Fully agree that a better quality food should ease the problem. However, for the occassional wipe that I need to give Rocco, I eased him into gettting used to it by feeding him a treat while wiping. Eventually, he'd hold still and let me wipe, knowing a treat was on the way for a "good boy butt wipe"
. I usually only need to wipe when he gets a "hanger" because he's swallowed some long hair that get it stuck and it dangles onto his fur (gross, I know).