Well, of course. It's not a substitute for actual roleplaying, you know? Apply a little common sense to situation, engage the NPCs in conversation, even put some work into investigating things. But if you're debating if you should give someone the benefit of the doublt, it's a helpful piece of info. If you're expecting supernatural trouble in the area, it's a good early warning. If you're going into an unfamiliar situation, it's a nice heads up. What I'm trying to point out is that the strength of the aura is just as important as the presence of Evil at all, and it can help you refine your reaction.