I see Earl quite a bit. Sometimes he's playing and sometimes he's just at the poolroom. He isn't always a terrible human. I'm not a doctor but I'm pretty certain he's bi-polar and under medicated. I once gave him a ride, maybe 10 blocks, to his apartment. He was nice enough and recognized I was doing him a favor. I would say the ratio of asshat:nonasshat moments are about 4:1 though.
In that movie they made about him they did mention he's bipolar, which could certainly explain a lot of his behavior.