Quite a few years ago - maybe before Alliant bought Hercules - there was a published report that the first lot of Red Dot ever made still performed as well as it ever did. Maybe Alliant will give us an updated report.
The smell test is a good one. What you are smelling for is NO2 which can also be detected as reddish-brown fumes. It has a very acrid odor which is rather unlike the solvent smell of good powder.
I bought a bunch of Red Dot and Green Dot in an estate sell 2 years ago.It was from a local store that had been closed since 1981.The Red Dot was in the all metal can.I bet the powder was from the late 60's.No problem with it at all and the price was right.
I pulled powder from 8mm nazi era mfg duds,and loaded them right into new cases with the original bullet, and fired so many with no problems at all,to the point I got sick of pulling the friggin` things,and gave the rest away.