Excellent question. We can test about 95% of the displays that we ship. We test for backlight functionality, "yellowing" -usually related to the color filter being old and discolored, dead or stuck pixels, vertical and horizontal lines, pressure marks, polarizer scratches, polarizer hazing, and cosmetic defects. We can also do very specific tests by requests -such as measuring the exact brightness and color temperature of each display, prior to shipment. For exact brightness and color temperature, this requires a request prior to purchase and will usually have a fee associated with the reporting as this can add quite a bit of time to our inspection process.