In my fraternity days, there was a constant fear of beer (typically kegged but also bottled) getting "skunked" as a result of warming up and cooling down too many times, possibly even once.
Do non-extreme temperature changes such as moving a beer back and forth from a counter to a refrigerator cause perceptible changes to beer? If not, what about more extreme changes, such as sitting in the bed of a truck or a trunk? I'm aware that light has a degrading affect on it's own, so let's assume this beer is in a keg or a light-proof box.