Trial Clothes I Recently Moved Into An Old Farmhouse. I Have Noticed That When I Line Dry My Clothes,?

I recently moved into an old farmhouse. I have noticed that when I line dry my clothes,? - trial clothes

it is a musty smell awful. When dried in the washing machine, unaware that smell. I can not imagine why. I tried the machine was in the case of the problem, and I hope Purewasher things to come, but over weeks of trial and error, it became clear that dry the clothes on the line are criminals. Does anyone know why would it?