Ask yourself why some chameleons have the "white stuff around the nose" but others don't.
Varying levels of salt in the water - cities have hugely varying levels of sodium, chloride and potassium in their water and most people use tap water for their chams. Have we examined everyone's water report to rule out this very obvious variation and leave calcium as the only possible cause?
Ask yourself why some chameleons have issues with excess calcium and others don't.
Whose? What problems do we see from excess calcium?