I suspect using "Detect Hate" a lot would likely give you a rather cynical view of your world. (Then again, I'm fairly cynical.).
Based on page after page of this thread, I suspect a lot of people are confusing the two spells. Most of the little e evil that people have delved here is either totally off the edge (the hungry beggar coveting your bread) or examples of Hate. . .like the boiling internal mental processes of a raging psychopath.
Notice that where it shows up in channeling "Detect Evil/Good" is "easier" (lower level) than scanning thoughts for "detect Hate" but the reverse is true for mentalism, where it's easier to sense hateful thoughts than to pick up objective Evil.
Beyond that, the "Taint of blood" on a murderers metaphorical hands is covered by "Death's Tale" and the like, so that's not the E-vil intended. (Heck, you can kill someone for the best, most high minded reasons and those death spells will still finger you). So a mass murderer will be like a beacon to those spells, but fall under the Evil radar, unless they also happen to be consorting with objectively Evil forces somehow.
Spells work best when they're specific and don't overlap excessively. . .and where the detect evil spells specify "True Evil" they mean objective evil, not mundane badness or less than nice thinking. . . .Essentially if any example you can think of doesn't involve undead, demons, Dark Gods, or compacts with such dark forces, odds are it's not "true evil" in the sense these spells intend.
