"Lonely" picture are better with a lot of contrast. I forgot to tone down the saturation on that one.
While "happy" pictures are less contrasty and have saturated colors with blown out highlights.
Not really. Cliche contrast definitely works pretty well. But usually flatter colours tend to be more dreary, more gray, more alone if you will. And it works often better.
Contrast works really well for strong energetic pictures. Or at least colour contrast.
Imagine a party again. You'll definitely get two colours there which strongly contrast against each other. - Green grass and vegatation and I can guarantee you that a lot of the highlights will be red. Clothes, balloons, party elements etc.
To cut myself short. The grayness and overall muted colours of the picture works extremely well. Since it evokes two feelings
a) some kind of disease (even made stronger with the dead in the background)
b) lonelyness.