I has a Texas Highway Patrol Officer (and a fairly hardcore one) tell that he once got the Department sued, or almost sued, when he worked a one car accident. The driver was seated on a low wall when the trooper arrived, and gave some mundane reason for running off the road. The trooper took his information for the report, and called for a wrecker, but not am ambulance because the driver insisted he was unhurt. He didn't ask the driver to perform any field sobriety tests because he didn't detect any indication that the man had been drinking, much less was intoxicated. While he talking the driver and waiting for the wrecker another call came in, and as the driver seemed fine the trooper drove off to answer it.
About 30 seconds after he drove out of sight, the driver got back into the car, drove about a few blocks, and died in another one car accident. His blood alcohol level was three times the legal limit. And that, explained the trooper, was why he always asked about drinking and did at least the HGN test (eyes) when working a wreck.
These days I can spot the chronic alcoholic mostly because you can smell it on their person. The acetic acid smell emanates from every pore on their body and their breath. Which is why the driver you describe was out of the vehicle.
My co-worker got tapped in the right rear quarter by a woman who didn’t stop in time and busted the tail light and dented up the trunk. He was an experienced alcoholic, and to the deputy didn’t appear intoxicated but he must have gotten a whiff of it by being down-wind of him. That little comment by the arresting deputy, had my co-worker going to AA and psychologists for years. Nearly broke him of money...never stopped him from drinking. Still a drunk to this day.