Alignments work a bit differently with this house rule.  Essentially most people you encounter will be neutral, with tendencies towards good or evil.  When trying to detect evil or good, you really will only feel an aura of that alignment from creatures that are powerfully imbued with it.  These creatures include angels, archons and celestials...good of course, oh and clerics.  Fey will usually radiate a chaotic alignment.  Undead, demons, devils, necros and evil clerics will of course radiate evil.  So humanoid races  such as orcs, or gnolls, or trolls will not radiate an alignment of course unless they are imbued with an aspect of good or evil or a cleric. Like a half-fiend troll will radiate evil cuz he is a half-fiend.