I know I am not the only person that has this problem. When I was my towels..sometimes they still have that nasty mildew smell. I thought it was my washing machine, so I cleaned that. Then I thought maybe I had left them in to long after they were done but nope. They just smell.
So here is a easy way to get them clean!
1 cup of vinegar
1/2 cup of baking soda
All you need to do is wash your towels in hot water with a cup of vinegar, then run it again in hot water with a half-cup of the baking soda. It will strip the towels from that nasty mildew smell and all of the gross residue that is in them. It eventually leaves them nice and fresh.
I do not add laundry detergent to the wash and I do not dry them with fabric softener sheets either. . I also only do this every month or so just so the smell is gone and they smell good.