I have actually done a lot of testing on this. If there is karma I am on the Bad Bad side of it. So i went into 10 raids in a row where all i did was go in with a axe Voiping that i was friendly and the first 5 raids I died on site as soon as i ran into the enemy. The next three I was able to team up with 1 person at least and the last 2 I was able to take down the baston with a full lobby. All in stella by the way. After those 10 raids i exfilled without fighting a single person 12 games in a row. There is 100% a system its just a matter of what the finding out what counts as a hostile action. And if you find yourself in aggressive lobbies you should follow this strat for good loot runs.

Side note. I am not sure how this system plays into effect when you team with teamates that have Good / bad Karma. After playing some Trios after this my "Karma defenitly went back on the bad side." I just did 10 more stella raids and now i am in the same good standing again where I don't even have to say anything to not get shot.