I'm trying to make actors that completely ignore the player. No Greeting, No Turning Towards the player etc. Anyone know how to do this?

I've got the beginnings of this in my port of my Oblivion mod Clothing matters.
Haven't gotten far, however, other than them not saying anything to you at all under some conditions.

What I have:
NPCs do not react to your Activate command depending on certain conditions (i.e. what you are wearing).
If you have Stormcloak cuirass, citizenry who side with the Imperials will ignore you.
If you have Imperial cuirass or Thalmor robes, those who side with the Stormcloaks will ignore you.
If you have the Dark Brotherhood or Assassin clothes, everyone will fear you and will tell you to go away.

I have plans on extending this to actual NPC Reactions (which I mentioned in shadeMe's Universal Silent Voice post: http://www.gamesas.com/topic/1351365-universal-silent-voice-possible-under-skse/page__view__findpost__p__20405700) where NPCs will not talk to you unless in certain conditions (i.e. in an inn).
Role-played, this is actually your avatar refusing to start a conversation with them - even if you, the player, activating the NPC.
Only certain conditions will start that off. One of them is if you have with you (e.g. Ralof) a friend of an NPC.

How I did the first part - i.e. the Clothing matters part.
(The 2nd part is just in my head at the moment.)

• detect when the player equips/unequips the different armours
  
• put that in a quest variable
  
• add topics to that checks the npc's factions
  
• if it's a faction that doesn't agree with the armour the player is wearing, the conversation exits
  
• i set this quest up with a priority so that my topics takes precendent over EVERYTHING that is in the base game.

Voila! In my current game, I followed the Imperial from Helgen.
When I put the Stormcloak armour, those who side with the Imperial in Riverwood (e.g. the smith that asks you to go to Whiterun) ignores me.
As a test, I followed Ralof from Helgen.
When I put Imperial armour, Ralof's sister and that woodcutter ignored me.