It never occured to me that thread could go bad. Like an expiry date or something. I inherited my grandmother's embroidery thread which now must be in the 70 years old category and it still sews up nicely. I keep my quilting thread in a flat tackle box with lots of compartments so the thread and bobbin together have their own space. Some of it is getting on in age and I've never wondered if it would work or not, it just does.
My MIL has a big fabric stash but arthritis now keeps her from sewing like she used to. She let me raid her stash. Now, I KNOW that some fabric was past retirement age but with a careful washing it's just fine. I guess the key is that it was dark and dry.
Cathe - you made me think about one of the cutest things I read in a book (Chiaverini) with your story of your friends stash. A quilter keeps each of her UFOs or planned packs separately in a box that she has labelled with the name of a friend or family member. That way, when she goes, her things are not only designated, everyone will believe she was thinking of them to leave something to.