Because Dominos uses SOY GMO...Papa John's uses products that are good for you. Dominos has modified there product year after year to keep up with junk food junkies...so when you eat junk food riddled with chemicals that's what you get used to.
Depends on what you get, and how you specify they make it. For example, I always get my thin crust baked well done. And everything from PJs gets a healthy sprinkling of Special Seasoning.
Personal preference
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