SeriousEats.com: The Burger Lab: Revisiting the Myth of The 12-Year Old McDonald’s Burger That Just Won’t Rot (Testing Results!)
There are many reasons why not to eat McDonald’s Burgers and fast food in general, but the fact that they don’t seem to rot shouldn’t be one of the according to this experiment by Serious Eats.
It seems that most burgers when left out, dry out too quickly for mold or bacteria to grow.