If you've been in this business for a year or more, you must have noticed by now the ratio of iPad 2's with LCD color problems compared to iPad 3-4-5 altogether.
The difference? Mainly the infamous iPad 2 display cable.
9 out of 10 times, I need to clean and reseat the cable ON BOTH ENDS. 1 in 10, the cable needs replacing. 0/10 I actually need to replace the LCD because of the blueish or reddish hue.