Dunno about the kind with real sugar, but the fake sugar breaks down to something foul tasting even if well-sealed. Shelf life may be longer than they say on the package, but I accidentally stored a 12-pack of Cherry Coke Zero for several years in my garage, and when I opened one up they tasted awful.

May be temperature-sensitive; while local weather is pretty mild the garage is subject to what by local standards are pretty steep swings.