I must admit I was kind of confused when I read the book (after the movies), and saw these references to Fredo not as this utterly obvious dumb guy; it was more dynamic than that, especially with the vague wording, and left room for debate. You know, maybe all these inconsistancies were really to give us something to talk about 30 years after the fact. Anyway, this thread has my mind working, and I think I'll go for another read and watch the films.