If my hand touches it, it most probably will be used in a quilt. I have used old dresser scarves in a winning quilt. Beautiful old crocheted lace with cotton backing was used as inset borders. If it looks right, use it.if its flimsy, back it and use it. However, if it's threadbare in places, save yourself a lot of grief and don't use it as its too far gone at that point. But, it could be salvaged and used in a wall hanging. No fabric should ever be wasted.