After hiking in humid conditions, it’s better not to leave mud to dry on your boots and let it get encrusted in the seams. If your boots are made of leather, the mud can have a drying effect on them and hamper their properties.
Leaving your boots to dry near a heat source may lead to damage. Too strong a heat will dry the leather out. It can damage the glue used to assemble the upper and the sole. It may also affect the reinforcement inserts, leading to deformation.
So avoid leaving your boots out in bright sunlight, at the back of a car, or by the fireside.