I am a little confused as to how the humanity score works. I've finished the game with many spills and very few spills but I always seem to get low humanity ending. What exactly affects the humanity score? Should I be avoiding the golden pipes to reach high humanity score?

Currently it is only the player viewing the customers being transformed that lowers your humanity. Viewing them is optional. The humanity score is faintly visible during these scenes in red text, however I may remove this one day.