Don't always spawn. Sometimes you have to walk by the spawn point a couple of times before the dragon spawn. Arid Sandstalker Dragon can come out of all the tunnels coming out of the wall.
Dragon Compendium
Found only in the arid deserts of Korhala, this predator burrows beneath the sand to lie in wait for its prey to wander by. Its rough skin and sharp claws make this dragon a formidable opponent. Many adventures have sought them near Aymori Sands, though most fail to return.