To me wiping the blue marks off or spritzing with water is a myth. In either case some of the color is going to penetrate the fabric. Sometime what we think are short cuts are not effective. I always recommend washing to be sure all the color is out from top and what seeped into the batting. This also goes for the felt tip pen that disappears in the air. The color might disappear but the chemical is still in the fabric and might cause cause in the future.
Yes, I know that many quilters say they have success with wiping or spritzing but I want to be sure all the color and its chemical is out of the quilt.