Bottom post of the previous page:
But nothing in that picture is anything to do with antags. I tried with many other items, such as a piece of paper, a straight jacket and a MMI with brain but they still didn't appear.Most if not all traitor & antagonistic items are invisible to photographs, unless in the case that is a agent card disguised as a off station ID in which it uses a non traitorous/antag sprite.
Lore reason is that it makes it harder to prove traitors, so everything traitor related is usually sprayed with anti-photogenic paint that repels polaroids etc.