Do refurbished iPhones have user data on them?

Refurbished iPhones are wiped of all pre-existing user data. 

When an iPhone is refurbished, its internal storage is completely reset. No video clips, text messages, random apps, or documents will clutter your refurbished device. The OS is restored and the storage is new. A refurbished iPhone is fresh and ready for its next user as if it were brand new.