Batteries leaking in the store package before they are purchased, with 8 year shelf life remaining, is likely not the fault of the person who hasn’t bought them yet.I don't know if this really applies to your guy's problems with batteries, but the issues that you are having is one reason why I don't buy batteries in bulk unless I'm changing my flashlight batteries. Batteries that just lay around for long periods of time are known for leaking and power loss
Batteries leaking in less than six months from purchase (in the package in a drawer) is also not likely influenced by the user.
There has been a significant change in battery life over the past couple years. I have bought batteries in bulk for more than 20 years, and rarely had them go bad prior to use.