While cleaning out my garage yesterday, I came across a dozen cans of assorted beers that had been lost to the world (and my fridge) for over 10 years. That's taking the age from the date stamp, which is mid 1997.
One can of DB had some nasty brown stains on top that looked like a leak so I popped the top and no, it was still sealed and fully pressurised. I tipped it down the drain and it looked as fizzy as normal so I had a sniff halfway through and it smelt quite normal as well.
I suspect that it was still actually drinkable, but I wasn't game to try. Anybody here ever been desperate enough to dring aged beer? Bottles go flat, but it looks like tins are another story altogether.
I'd put them on TM as "vintage beer" but I don't think you can auction liquor.