His thing is that he does chapter-by-chapter readings of things, cold, and posts about them, but with Pratchett in any case he is tending to misinterpret things because he's reading without context and to assume the most negative interpretation applies where there's a choice. For instance, in Soul Music where there's a raven who can't bear people saying "the N-word" (Nevermore), and Mark decided that this was grossly offensive because it must be making a joke about an incredibly offensive term (the other N-word, obviously).