Why is my Cycles scene so bright even with no lights? Apparently cycles has some kind of built insane glow that causes everything to be brightly lit in a scene even with no lights at all and all light sources removed. How do I turn this insanity off?

I tried setting World > Surface > Color to fully black, but it does nothing at all. I also turned off Ambient Occlusion under "World" but no change either. Of course every single light in the scene is deleted but it still renders bright as a floodlight shining directly in your face. >:(

What am I missing here?
Most likely Ambient Occlusion is enabled. Go to Properties > World and just turn it off: 

 

From the manual:


  Ambient occlusion is a lighting method based on how much a point on a surface is occluded by nearby surfaces. It simulates soft global illumination shadows by faking darkness perceived in corners and at mesh intersections, creases, and cracks, where ambient light is occluded, or blocked. This is a trick that is not physically accurate, but it is useful to emphasize the shapes of surfaces, or as a cheap way to get an effect that looks a bit like indirect lighting.