I said to myself well it was just one bad deed, I'm sure that I can get it lower by doing other things. For instance I started a new play through about a week ago and I wanted to see how bad I could get (I've tried it in the past without success but I figured I would try again) and even at the beggining of the game when I chose to wipe out goodsprings completely I only had neutral karma.
It is almost impossible to have a bad karma score in the game, now I don't know if it's just me or if other people are having this problem too but even when I go out of the way to be bad I still can only get a neutral karma. And while there were many things that I enjoyed about the game I feel like this was the one big thing that I disliked about it. I am a huge fan of fallout, especially New Vegas.