If you leave a beer out, it can take on a gross, "skunked" taste. It isn't because of the temperature, though. It's because your beer is absorbing extra light. Keep it away from the sun to make sure your beer stays fresh.
Photo by tab2_dawa.
As advice site Man Made DIY explains, the hops in beer is sensitive to ultraviolet radiation. If beer in a clear glass bottle is left sitting in the sun, the hops will partially turn to sulphur, resulting in a rotten flavour and a ruined party. While you might have heard you need to keep beer cold to prevent this, technically it's being in a dark fridge that prevents the skunking flavour.
This is also why so many beer bottles are a dark brown glass. The darker colour filters UV radiation, to prevent the skunking flavour. Of course, some beers still come in clear bottles or other containers, so if you have some of those, it's best to keep them out of the light. It's better still to buy beer in a dark bottle or opaque can, straight from the fridge, and then keep them in the refrigerator. The temperature may not affect the "skunking" flavour, but if you keep them in your fridge at all times, you'll never risk one that is not cold.