I completely agree... the facts are generally revealed as the story goes.. or should be in good stories, but at the end, when the "hero" (or heroes) solves the case, all the informatino should be there that the audience could too... i agree with you that it's cheating (or "arbitrary difficulty") if the hero goes "aha! i got it!" and the writers can only make him look brilliant by having the solution require information that was never given to us until post facto them solving it.