I'm excited to finally find a topic where I can make a contribution.

That said, I can only add a few points. The most common way to shorten the "shelf life" of fresh milk is by improper handling. Milk should be stored at a temperature of 41 degrees F(5C) or less. Food service guidelines state that if it remains above this temperature for more than 4 hours, there is a significant risk of dangerous levels of pathogenic microorganisms (bugs).

Experience tells me that milk that has remained well chilled will usually last 5-7 days past the "sell-by" date. In areas such as my home (Texas), it can be hard to get it back from the store in the summer at the proper temperature. Can you say - I hate warm milk!

If you are in good health and are not immune compromised, you can probably deal with a little sour milk with no lasting effects.