It's a double edged sword. You won't be losing any mood for killing if you pick the psychopath trait, but you will never get any bonuses either.
Without it, you will get heavy penalties at the start, but these will get lower with time and will even turn into actual bonus to mood if you get evil enough.
...but the net effect of all the things I'm doing (killing everything I can, talking to everyone, doing as many quests as possible... i.e. completionist behavior) seems to be to gain Good, not Evil; and I generally prefer to be Good in games anyway. So I'm only going to get the Good perks, not the Evil perks.
The morality gain is pretty barebones and it is skewed heavily to being good. You get good points for talking and what not, but mainly for killing abominations, which are much more plentiful than humanoids and are placed in areas with better loot, so the average player will naturaly kill more abominations than humanoids and thus never get enough evil points to get these perks.
There are more ways to get evil points. Doing drugs or drinking alcohol is one of them and refusing to help strangers in random events should also give you negative points.
That said, being good is still quite benefitial, especialy when you take into account what I said at the start, because good perks actualy lower the mood penalty you get from fighting abominations, which didn't happen in previous versions. So you can kill some humanoids and then kill some underground enemies to get your mood back.
Negative morality is gained by killing humanoids (kobolds, bandits, swamp orcs), killing animals (Boars, scavengers, cave crawlers, wild dogs, boglings), drinking alcohol, smoking, doing drugs, rejecting to help random event NPCs.
Again, this is because the system is, like most systems in the game, unfinished. To be evil, you pretty much have to avoid doing a lot of activities, because they raise your morality. Being good on the other hand is quite easy, since you get good points for pretty much anything and abominations are easy to grind.
All of this will change in future versions as there will be more ways to be good or evil. I will also add some kind of perks that affect your morality in some way.
