It’s not a dealer’s issue or has anything to do with changing times. Everyone will or already has had that experience at least once. You’re just too inexperienced. ​There are many reasons why milk can go sour, as we call it here. Most depend on how you as a consumer handle it. ​Some are just bad luck. For example, if there was a thunderstorm, it’s more likely to turn into an ugly buttermilk mess. ​Don’t blame Walmart or the milk, because you can’t be sure if it wasn’t your fault.