Uniformity assessment: It’s not worth attempting to profile a display if it significantly fades at the corners or has a localised color cast, as any judgements you make will be affected by this. A quick way to visually test uniformity is to set a neutral mid-gray desktop pattern and close all windows.
Older-style CRT displays usually have controls that allow you to adjust for mis-aligned screen display and various other screen geometry faults, but there isn’t anything you can do about a faulty LCD panel; be aware that LCD manufacturers do specify tolerances for uniformity and defective pixels.