I don't think they are a complete scam. They can be used to improve your chances in a really tough situation. I have bivouacked with less in grim conditions where I would have welcomed a foil blanket, had they been available at the time.

It is misleading to talk about their ability to reflect most of your radiant heat, neglecting to point out that most of your head loss occurs though conduction (unless you are in outer space), but we find that out pretty quick, don't we?

Like most of us, I have pretty much gone on to Thermolite and other better products. Also, I plan better than I did when I was a kid....