IT IS POSSIBLE. Some actions rise your overall rep, some lowers. When Xenos are at -9 blocks to the left (red/hostile) killing them does not change this, but changes other factions, generally in +. Same with others. There is no sense to fly for or bribe the Outcasts, Corsairs and Xenos (in terms of reputation), and there is a sense to do this for police or companies up to 8 blocks to the right as I mentioned erlier. Further actions will make less good or even will lower your overall rep.
And the chain of reputation changes is only 1 level deep,
ie. You kill LSF, LPI goes down but that change (LPI) doesn't make LPI friends to dislike you more. Unless they are LSF friends too .

And I AM friendly with all just playing the game, so don't tell me that I've done imposible things. This is the FACT. If you still not belive in facts, it's your problem.

Tygrys

Using the Empathy.ini edit described elsewhere does actually increase your "invisible" rep with the Nomads. I can fly around the Unknown Jump holes and Unknown systems and the Nomad fighters that hang around remain neutral. Since the Nomads have no entry in your reputation listings, killing them only makes you hostile with them. IF you do ever get on their bad side, you just go back to Slaughtering Xeno's again.

I just don't count Nomads as faction in the game, so maybe I am not a friend to everyone in a game. Everyone human should I say. But my oficial reputation list is green from the top.
Sure, editing ini can give you a good reputation with everyone. But that way you can have a good ship, lot of money, level 50 weapons, shields and whatever you want. No reason to fly anywhere.
What I want to say is that you can have green status with all factions on the reputation list, just playing the game, no mods or cheats. Something that DA have told to be impossible.
Thats me who did that . Anyone else

Tygrys

I am always friendly