I think I seen this mentioned before here or elsewhere.

Anyhow, a thermochromic ink spot could be printed on the can, although it won't show core temperature, as that would be too expensive.

2 words:

Bring ice

This would be a very inexpensive marketing tool. The coldest Beer or soda in coolers could easily be identified by a temperature sensitive dot being placed on the top of the can. Cans put in a few minutes ago would be much warmer than cans put in 10 minutes ago. But realistically, this idea is a better idea from a marketing point of view. If Coke and Pepsi were in the same cooler, and the Pepsi and you could readily see the Pepsi was cold, you might grab the Pepsi instead of the Coke.

Great Marketing Idea!!!

This post was probably done pre-Coors cold can was invented. However, good job seeing a possible gimic to market. Coors may not be using a thermometer but the Rockies turning color provides the same purpose of your example! Kudos ShawnP!!!

The Coors can uses the thermochromic ink I mentioned.

Soda can in fact expire. Proven to me by a really hot girl, which is good enough for me. We happened to have some drinks past their expiry date out on the sales floor, and they did indeed taste bad upon inspection. (Probably something to do with flavors and other compounds surviving in a strongly acidic environment, but damn, did she ever look fine in fishnets!)

The Big Duo now puts thermometer displays in their vending machines (although it says nothing about the cans themselves). In any case, the Mythbusters showed that salty ice water can solve any lukewarm problem in about five minutes.