This is an old post but I think it's worth reading.
@SuperTmo
“My job with the organ / eye / tissue bank that I referenced earlier started out as a tissue recovery tech. I would take veins, heart valves, skin graphs and various other anatomical gifts from recently deceased people.
All that to say I did recoveries on over 150 bodies of all ages and never once did I see anyone blue. Grayish, maybe? Lots of pale people. Some bluish lips. Recoveries were usually within 8-12 hours of death. I did see a few suicides by hanging that were probably more like slowly strangling but they weren’t blue either. One was fairly red faced, but the other two were just sort of whitish with blown capillaries around the eyes and on cheeks”.