Not everyone has the same response to LCDs in terms of ghosting and bluring. Some people cannot detect the difference between 30 FPS and 60 FPS, and some people cannot detect the difference between 60 FPS and 90 FPS. Some people can ever detect FPS if it falls below 100 FPS. With that said, some peoples' eyes are simply more sensitive to the LCD block changing colours that they do see a ghost appearance on the switch. Some people are fine at 30ms, some at 16ms, some at 8ms and sometimes only 4ms.