I bought two of them and the one I used I never had a problem with mold. I didn't try to use it for dehydrating, I bought it for sprouting. I live in Florida and once when I went to check on a tray of sprouts on the back porch, it had a giant palmetto bug nestled down in the roots! So I went online and found these. The screening zips up securely so no bugs can get in. That's really why I bought it. It's nice because it has 5 trays so you can sprout A LOT in it. That's why I never even opened the second one. I was sprouting a lot of sunflower seeds.
It hangs up so air can circulate all around. I don't think you'd have a problem with mold. You could set a fan to blow on it too.