I guess it's all down to how you play it, which is - I imagine - why the thread was started in the first place
The way
I play it is that most PC's and NPC's haven't done enough "objectively-evil-stuff" to have accreted a significant quantity of badions: they hardly register on the moral geiger counter. However, the way I
also play it is that creatures with an alignment subtype, clerics, paladins, blackguards
and creatures who belong to races listed as always having evil alignments have a high enough badion particle component that they're always detected according to the table.
Meh, whatever, it works for me

I've run it differently when the setting seems to demand it, Ravenloft being a particular case in point.
The weird thing about being evil in D&D is that it is a choice that makes
sense, uncomfortable though that may be to contemplate. Evil creatures are judged by evil gods and go to evil paradise when they die, good creatures do the opposite. Evil people and creatures in D&D can just think of themselves as "Evil" and not worry about it: after all, there are just as many deities in most settings affirming Evil as a valid lifestyle choice as there are Good deities saying otherwise. It's only creatures who are
supposed to act according to one philosophy and actually
do the other who suffer, as they'll be judged harshly by their gods when they die.