I find that with my thrift store finds. Many times a thrift store will get a ton of fabric from someone who has passed. Occasionally that fabric can smell musty. Being the frugal person I am I usually grab the fabric and I will wash in vinegar/laundry detergent and that takes care of it. I agree hanging on the clothes line outdoors works wonders but for those of us in the chilly winter climates that is not an option.