I still believe that "simulate paper color and black ink," when checked, tends to overstates the effect, making the soft-proof duller, which we then tend to compensate by increasing the contrast. Or we need to be very careful when using that option not to have anything else on the screen (i.e., viewing the image in full screen mode) and not looking at the screen when turning it on (also avoiding switching it on and off in rapid succession). All this because our eyes/brains adapt to the lower contrast, but if we do not give it enough time, or if we keep going back and forth, the soft proof would appear too dull in comparison, thus making us increase the contrast too much.