How to purchase a used Apple Watch? What necessary and sufficient steps can one take, from the software side of the device, when (s)he is purchasing a used Apple Watch, to make sure the Watch is what the seller is claiming it to be?

Are the steps different for GPS and GPS + Cellular models?



I have never used an Apple Watch before. Would just syncing up the Watch my iTunes be a necessary and sufficient way to ascertain if the Watch is ok to purchase?
From the software side, all one needs to do is:


Update your iPhone to latest iOS;
Reset the Apple Watch (You can do that from Watch itself);
Setup the Apple Watch using your iPhone.


Once it is paired to your iPhone, it is safe to assume that the device is off the previous owner.