A dell employe responded regarding the backled bleed on the dell forum :
Uneven Backlight or Color
* We do not validate our monitors in a dark room. We use standard office lighting
* Dell monitors do not have 100% backlight uniformity specification. As long as the center 2" circle meets our manufacturer specifications, it is acceptable
* If the Brightness and Contrast are maxed to 100 and you measure the brightness difference of any two points on the monitor, the difference will never be greater than 25%
* Dell monitors do not have 100% color uniformity specification. As long as the exact center 2" circle meets x=0.313 and y=0.329 (6500K), it meets our manufacturer specifications. So, the center may be 6500K, but the sides and corners may not which is why you may see that one side or corner is different than the others
http://en.community.dell.com/support-forums/peripherals/f/3529/t/19466444.aspx