Actually I for one gave up Death Note in frustration very early on because I couldn't help focusing on how much of the real inferential work was being done by the authors feeding the correct answers to the characters. Like when L concludes that Kira must know the victim's real name to kill him... there were so many reasons that just didn't work. Kira's apparent modus operandi was to kill criminals, there was no particular reason to suppose he would respond to a challenge to kill anyone else, so the fact that he didn't was already weak evidence regarding whether he could at all, let alone what the restrictions might be. Whether Kira knew his real name or not was just one variable switched between him and Lind L. Taylor. L could just as easily have been immune because he eats too many sweets.

While smart, knowledgeable people can often extract a greater yield of inference from a limited amount of data than others, I find that far too many writers take this idea and run with it while forgetting that intelligence very often means recognizing how much you can't get out of a limited amount of data.