What do I consider faulty advice for the marathoner?

For me, it's the "decrease miles-not intensity" during the taper. I've had more success with doing a larger part of the run at warmup pace but forgoing rest days. If I run a week at the low end of aerobic pace with a slight speed-up the last miles, that won't lose any conditioning and reduce both madness and injury.

Also, don't "load" carbos--forget group pasta feeds! Just eat a higher ratio and avoid too much anything race morning... Maybe I'm the only one who gets nervous before marathons, but I will only eat a little toast, or some Ramen noodles race morning...maybe a Cliff bar. But I'm big on taking 2X the gu recommended. My legs have more spring; I don't care why.