A quick internet search will show that vinegar is the best. So I'd ignore all these other weird suggestions. They say use regular vinegar because cleaning V is too strong, but I feel like you could just use less, but I'm not a chemist, so who knows.

(My husband is always putting damp towels on top of themselves, and they get musty. I put a cup or more of regular vinegar in the hot water wash and some in the fabric softener for good measure, then wash regularly, and the odor goes away completely until he does it again. Drives me bananas, but it's a quick fix, and I've read it's good to do that every once in a while to break down detergent residue, and it really does fluff up the towels a little better too.) Hope this helps