“...Well, as it turns out, beer tends to lose its carbonation and become stale in plastic bottles, whereas soda does not.”
Just this morning while looking through the pantry for the BIG bottle of Bailey’s (to refill the small bottle in the liquor cabinet - medicinal purposes dontcaknow) I uncovered plastic bottles of Diet Coke and Canada Dry Tonic - both with their sides caved in — clearly all of the fizz is gone from these bottles...
Yes, everything can get stale in plastic. Have an unopened non-carbonated water bottle from my daughter’s undergraduate graduation, 2005, and it is doing a great imitation of a plastic raisin.