The humidity is really high, as it should be. The lid has a pair of small 2mm by 4mm holes in it, and I open the lid (which is about 4" by 6") for about 10 minutes each day. The frogs all appear fine and healthy.
I usually atribute bad smelling "mildew" as bad for the frogs. Could also be bacteria which thrive at high temps and high humidity, bacteria tend to create a bad smell. All my tanks smell like the woods not stinky just woody. I do get quite a bit of mold however its not smelly just shows up time to time.
Thanks for the advice, all. I moved the heat pad to the side of the cage rather than the bottom (it's not right up against it) and didn't lock the lid down (it's way too heavy for them to lift) and the smell has gone away.