[skeletor_999]

I think that the language we use might be limiting our analysis of this topic. We often describe minor keys as sad, but I don't think that really describes the emotion. Dark is also used, but doesn't necessarily imply sadness. Dark has problems too, as it's more vague.

Even though many people would describe certain songs as sounding sad, I don't think that it usually makes them feel sad. Can a song be sad if it doesn't make you feel sad? Heavy metal wouldn't be popular if it actually made you unhappy. Personally, it can improve my mood if I feel sad. Conversely, a really "bubblegummy" pop song would get on my nerves, but I would still describe it as sounding happy.

I'm not even sure that we could come up with better labels using common words. The emotions caused by music are pretty unique (at least for me).