Was he always like this or has his increasingly bad attitude gotten worse with age? You watch old Earl videos, and while he might beat himself up for a bad play, he's well behaved. Seems like he changed for the much worse after 2000 or thereabouts.
It has definitely worsened over the last 15-20 years. At his peak in the 80's and 90's he was an intense competitor who was all business at the table. He remained focused on the match until it was over and was almost always a good sport during the course of the match. He might shake his head at a bad roll but not allow that to affect his next shot.
One story I like to tell is from a match he was playing with Shannon Daulton in Reno in the early 90's. I was the TD and sitting on a podium directly in front of his table. As usual, Earl was putting on one of his patented displays of cue wizardry, running rack after rack flawlessly. He was on his six or seventh rack and Daulton was sitting in his chair, near comatose. Earl had a tricky shot to get from the five to six ball and he hit it good but the cue ball rolled a little too fast and scratched into the side pocket.
Shannon sat there stunned. It was his turn but he wasn't sure what to do. He didn't expect to be coming back to the table...ever! Shannon slowly approached the table (I could see he was confused), looked around for maybe ten or twenty seconds and then took the five ball from the side pocket and placed it back on the table in the same spot it had been in before Earl's previous shot, close to the side pocket. He now took BIH on the five ball. People were smirking and laughing in the stands. I have to admit I was slightly amused as well but as the TD I couldn't say anything.
Shannon got down to shoot (it would have been a foul the moment he hit the ball) and Earl stretched forward in his chair and reached out with his cue across the table to stop Shannon from shooting. Shannon looked up and seemed to come to his senses. Earl said, "Put the five back in the pocket." Shannon looked around and a big grin came across his face. He was embarrassed but relieved at the same time. He now took cue ball in hand on the six ball and completed the rack.
Earl won the match something like 11-3, but what I will never forget was Earl stopping Shannon from fouling. Earl impressed all present with that simple gesture on that day. Too bad that Earl is no longer with us.