I think one of the reasons I tend to stay away from gory films like that is that I have a horror of people bleeding. When I was a child, I was staying with my grandparents and one night as we were eating dinner, we heard a terrible crash. Two cars had collided head on at a curve in the narrow road near their house, with one young man not wearing a seat belt. He was retrieved from the car to rest on a chaise on my grandparents' porch until an ambulance could arrive. His head had struck the windshield and he was bleeding profusely. His girlfriend, who had been driving the car, was hysterical (understandably). I kept trying to help calm her, offering her a glass of water. I must have been around 8 years old.
Shortly after that, I began to experience fainting spells when the topic of blood would come up, or if I had to have blood drawn. I passed out in a Red Cross First Aid class and had to get excused from 2 weeks of my 8th grade biology class in which the circulatory system was under discussion.
I have managed to suppress this phobia over the years, to the point where I can now competently administer first aid to people with bleeding wounds, but the prospect of seeing people hurt really bothers me. I cannot explain this except for the odd experience of witnessing this traumatic experience as a child. The man was not fatally injured, but he was clearly banged up, requiring a trip to the hospital. Hearing the distressed cries of his girlfriend must have really affected me in ways that are difficult to explain.