I often have trouble knowing if I'm looking at a back-face or if it's just the way the viewport is currently oriented that makes faces look black (default color for back-faces). I find myself constantly rotating the scene around in perspective to get the light to shine on the suspect faces. I've tried using the 2-light and 1-light option for lighting the scene, but neither makes a significant difference to my tired old eyes.
If we had the option to specify our own color for back-faces, this wouldn't be an issue since a face in shadow would (should) still display in the chosen back-face color and a "black" face would then only indicate that it's in shadow. At the moment it could be either or both leading to unnecessary scene manipulation just to determine which it really is - shadow or back-face or both.
