The brand I buy, the plastic milk bags are tinted blue. I always thought that was so you could find that snipped corner triangle of plastic if it dropped on the floor, (they are are a choking hazard for children!) But maybe the darkened bag helps preserve the contents much like coloured vs. clear glass beer bottles?

Milk-in-a-bag is the most normal, mundane thing I've ever seen on Neatorama! As long as it was "neat" for someone, that's great. I live in Ontario, Canada and yes, this is how I buy milk. It's half the price of buying it in cartons. No one yet has commented on the awful occurrence of a bag leaking in the fridge. When that happens (it's very rare), it is NOT GOOD! I have three of those plastic milk bag holder jugs, and immediately upon purchasing a new 4L "bag of bags" will put the three milk bags in their holders. That way, any leakage will be contained. Another poster mentioned punching holes and making a "milk fountain" instead of just cutting off the corner. Here's another fun one... cut two small notches, one on each side of the bag tip. A stream of milk will come out on each side, making a V shape... fine for the cereal bowl but not good if you're aiming at a teacup!