The genuine "Space" brand space blankets, gold on one side and silver on the other, seem to hold up reasonably well in storage. Good items for first aid kits.
Sorry for your experience. The only time I've truly used one was a nap on the climb of Mt Whitney at the high base camp (about 10K feet). Breezy, on the granite rocks, huddled with about a dozen other boy scouts (I was 15 - not creepy like it would be now!). Anyway, got a decent little 3 or 4 hour nap. Stayed pretty warm once I'd tucked all the corners and feet in, but I also was wearing my normal hiking clothes.
I have a few heat sheets too, but I dropped the $20 on the Gen 1 Heatsheet sleeping bag. After having the above hassle of trying to arrange my "blanket" to keep the wind out, it's worth the extra money.