Magic The Gathering cards, pretty sure it’s some part of the lamination process. Under the house smell, earthy aroma that has stagnated for a few years. Moss covered valleys and crevices, basically where moss is so concentrated that it just jumps into the nose.
Dude was eating moldy or rotten food. There’s no way that he couldn’t taste something wrong with it. Probably thought, “This tastes bad but whatever.” Remember people, do not go “whatever” when it comes to food.
If it tastes bad, is slimy, was left out for a long time (dairy or egg more than 2 hours, moist food more than 4 hours, dry baked goods more than 12 hours), then throw it out. We have coolers and fridges for a reason. To slow down bacterial growth to preserve food for some short term future. Freezers for a lot longer. Use the freaking tools you’ve been given.