Personally, I am skeptical - of pretty much everything.
For instance, the missus was concerned about taking old TUMS.
TUMS are mainly Calcium Carbonate. CaCO3 is a chemical. It can't rot. Stored properly it will last until the end of time. So I told her, please don't worry about the TUMS.
Oil, Solvents, rarely go bad as they sit in a can on your shelf. Though paints, I believe, can go bad. Especially Shellac and Latex.
Even the FDA admits EXPIRED DRUGS are actually useful far beyond the date on the bottle. Though many will provide reduced effectiveness.
Canned Food, in my experience, is different. Some gets really nasty with age. I tend to toss it when it's past its prime.
SO ON THE THE POINT....
Kimber has EXPIRATION DATES on its PEPPER SPRAY.
Does PEPPER SPRAY really go bad ? Have you experienced FAILURES or SUCCESSES with old sprays ?