Gotcha. I haven't seen that in either my synthetic Land's End polar weights or merino. What I get is smell that is hard to wash out regardless of type of material (I'm just a smelly person ) - The only thing I've found to remove the sweat smell is a cat urine Biobased product (actually works for other organic stains as well) - not sure it is great for natural fibers such a wool, but it works.