I shipped home a case of MREs I found in the atttic of our barracks in Germany in 1993. I don't know how old it was at that time. It was in my mom's pantry, and a couple of years ago she found it and asked me if it was any good. I told her to call the bomb squad for hazardous disposal. I opened it up, and I think some of them were actually vibrating. One of them was (wait for it,) Beans and Franks. Oh yes, I'm THAT old.
No, I did NOT open any of them to see if they were still good.
In Germany, we would have to keep x-number of MREs on hand as emergency rations, we stored them on pallets, stacked in a special staggered way that let a few inches of air between every case. There are also requirements for mouse traps and poisons, temperature, and inspection intervals, but they are supposed to be good for 8 years from date of manufacture.
I remember when I was a boy scout, and our adult leader took us out to the woods for some service projects, and fed us MREs for the meals, and we thought it was the coolest freakin' thing in the world.
When I came back into the military after a ...long interval, I was pleasantly surprised by the new 'light' brown bag MREs. All of them have something good in them. At least compared to the old ones. Someone told me that the army pays $18 for the new ones, but I don't know if I believe it, they retail for less than that.
I tend to hoard them. We will go out to the local woods for a day and a half for drill, and I'll take a couple with me. I'll get issued four more, and usually come home with five. I know, curious hobby. I have them kicking around in my trunk and garage.