Colour Purity on workstation displays

When it comes to colour purity of an image display device, what critieria would you use to accept or reject the performance of a display unit?

For example; while displaying a 75% full field white signal, you reject a display when:

1- I can easily notice a colour shift with the naked eye.

2- I can barely detect a colour shift with the naked eye.

3- I can detect a colour shift with the naked eye which occurs just around the perimeter/edges of the display.

4- I can detect a colour shift with the naked eye which is spread out all over the viewing area.

5- I can not see a colour shift but my calibration probes indicate there is one.

6- I don't care about purity.

Cheers.

Bill