How do you figure out the “Use by” date of a food product?

Question: How do you figure out the "Use by" date of a food product?
- Keywords:
  food,
  health,
  nutrition
Asked by Zealousy to Chris on 15 Jun 2015.
- Chris Armstrong answered on 15 Jun 2015:
  
  The conspiracy theorist inside of me is screaming that “Use By” dates are incredibly vague and simply one method of preventing lawsuits and encouraging repeat purchases.
  
  But a less skeptical view is that its a study of the growth of bacteria vs the preservatives in the food. In the case of meat, once its no longer “kept alive” (as in still a cow) it’s beginning to decompose, bacteria will speed up this process and rapidly cause meat to spoil unless something is done to prevent the spread of bacteria. Such as freezing, adding preservatives or vacuum sealing, all of these (to a certain degree) halt the production of bacteria and enzymes that spoil the meat.

Question: How do you figure out the "Use by" date of a food product?