In an article on proofing you wrote, with regard to the "simulate paper color" button, that you have never found it satisfactory and it was sometimes disappointing. Then you recommended leaving it off unless you have a good reason to use it. Playing around with it, it does appear to make a dramatic difference with certain papers. Is your objection that the results shown, on the monitor, by pressing the button are just not reliable? If so then what would constitute a good reason to use it?