Some people drop their phones more than others. Its also called being foolish. Believe it or not there are some people who don't put themselves in the situation of potentially dropping there device like myself they don't have to worry about things like this.
Kind of luck unless the person selling it is ok with admitting what he has done with it.
Mate of mine bought a GPU with terrible artifacting, claims its normal for "certain games" (all games), must have been pushed too hard before.
Friends of mine used this to get the locked cars as they didn't have it on console.
https://www.gta5-mods.com/misc/exclusive-content-for-returning-gtav-unlocker
Good for him, I wouldn't personally lay off people if I was making that per year but it's his choice, it's not like anyone else has better experience running Microsoft.