Moving away from statues, the gods' forms are projections designed to play with mortal cognition. They can change their appearances, based on the desired impact of a god's visit (the aptitude for perception of those whom they visit) and the god's aspects, as ascribed by each culture.
Indeed. I imagine even Mehrunes Dagon could assume a harmless looking or at least not hideous form, depending on the type of destruction he felt like promoting at any given time. Remember that Destruction takes many forms. Not always a big explosion or a raging forest fire, but sometimes as a slow acting poison or a deadly toadstool which looks exactly like a harmless mushroom.
And in those stories about Sheogorath that MK wrote for Shivering Isles, didn't Malacath appear as a normal looking cloaked Orc warrior in his story? Rather than the giant, cleaver wielding monster he's usually depicted as.