Last night I took out a bottle of my standard American Amber that had been in the fridge about 6 months. And one of the same recipe that was only a month old. We did a test with three glasses, with folks trying to figure out which of the three was "different", and then if they got that right, which was the more aged beer.
Out of four of us, only one identified the different beer, and he got the aged vs fresh wrong.
I was happy with those results. Plus, it was fun to do.