Does dynamite "go bad"?

The old gentleman who lived across the street from me passed away some months ago at the ripe old age of 93. He had a little house which is situated on about a half acre of unfenced land. He was an absolute packrat and a collector of the most amazing assortment of items - bath tubs, lengths of wire fence, building supplies, metal wash tubs - you get the idea. Much of this stuff is just lying around outside his house. I sometimes take a shortcut across the upper part of his property when I'm walking back home.

Well, the other day, Starshine slipped off her leash and happily ran off to inspect the many treasures scattered around his place as we were going back toward my house. I finally managed to catch her when she had got into an old shed to chase after a ground squirrel. There was a punch of discarded lumber in the shed and 4 sticks (very old) of TNT.

I must confess that the thought of having my very own stick of dynamite had a certain allure, and the old guy wasn't going to be using the stuff, so I swiped one of the sticks.

I'm not planning on blowing anything up at the moment, but I'm wondering if the stuff would still work after 20 years or so of laying around? Does anyone know? I suppose I could go way up in the mountains somewhere, light the fuse and run, but is there any other way of finding out?