Yeesh, a fireball leaving your clothes untouched is hardly the biggest gotcha with D&D magic. Consider, for example, how a disintegrate affects you, but not your items (except on a roll of 1 on the save). So you end up as a little pile of ash, and all your items, which are still intact, fall on top of it in a heap. It brings to mind Daffy Duck's disintegration-proof vest in Duck Dodgers in the 24 1/2th Century.