At this piont, I keep feeling that I should mention the Detect Evil spell. If you look at the list, you'll find things like "Cleric of an Evil Deity," "Undead," "Evil Artifact," and "Evil Creature." None of the categories mention someone of an Evil alignment.
The argument can be made that Evil Creature means he of an Evil Alignment. I would point out the many instances (notibly in the Domains section, especally the Fire, Water (or is it cold?), Earth, and Air sections) where they list Fire and Air creatures. This doesn't refer to Fire Elementials only. You can turn/rebuke a Red Dragon if you'd like.
Without the Evil Alignment, the Detect Evil aspect of a Paladin is sorely limited. It also removes many DM headaches.