Maybe I'm not understanding what it is meant by bright/dark scene. So, let me change the terminology to over and under exposed scenes instead. To me, an over exposed is a bright scene and to correct that, one needs to set the Ev to a negative value (-0.3, -0.67, etc.),while an under exposed is a dark scene, which can be fixed by increasing the Ev value (+0.3, +0.67, etc.). At least, this is how my H1/FZ20/D40 cameras work. Now,perhaps the EV implementation is different in other brands/models, I don't know.
It is confusing and bass ackwards, but the camera's metering system will try to meter everything to 18% grey. So if you shoot outside with a bright sky and white snowy fields, your camera will try to darken it to 18%, not knowing that everything is really white, so you need to dial in some positive exposure compensation to brighten things up to where they should be. That is not the same as a scene being overexposed due to too high of an iso, wide open F stop or too slow shutter speed. You will see it in some shots of a snowy landscape (and some of the shots in this challenge) where everything has a dull grey color, some cameras have more of a blue bias and the snow (or white color) will be more blue than white. The opposite holds true for darker scenes, though I'm not too sure how that affects the colors. Some cameras obviously have better metering systems than others so maybe it isn't too much of a problem for yours. For a test , put your camera in auto and fill the frame with a white sheet of paper and see what color it really comes out, then try some + exp comp. Hope that helps a little and didn't just muddy the waters more.