"Blood, Puss, Decomposing flesh, carcinogenics and bacteria." answer is weird. I'm sorry to burst anyone's bubble here, but I work in the food industry and I can tell you that almost everything is carcinogenic and you have no idea how many people cook their food in ways that make the food carcinogenic. As for bacteria, all food has bacteria, especially things that come from once living things. The way we cook it kills it off as much as we can on it but what's left on the food just won't harm you. If you're a meat eater, I'm sorry to tell you this, but you still eating the blood in the meat. The only difference is that the blood is cooked and you don't see it.
Again, for meat eaters, in a study conducted by the usda they found that 78.6% of ground beef contains microbes that are spread primarily by fecal matter. Don't know what fecal matter is? It's pretty much feces, also known by many other names, is a solid waste product from an animal digestive tract, discharged through the anus or cloaca during a process called defecation. Urine and feces together are called excreta.
How about decomposing flesh? I'm sorry to tell you this, especially meat eaters, but decomposition in animals is a process that begins immediately after death and involves the destruction of soft tissue, leaving behind skeletonized remains. The chemical process of decomposition is complex and involves the breakdown of soft tissue, as the body passes through the sequential stages of decomposition