I've always been inclined to believe the witnesses and really focus on the finer details of what they said. Florence Schaffner in 1988 on Unsolved Mysteries always lingers in my mind "the sketches never really looked like him, it's still STRONG in my mind, I still see him...wide forehead, narrow face the hair was wrong..."
I produced an article under the suspects thread last night which has an interview with ticketing agent Hal Williams, holding Bing Crosby sketch, claiming "the hair was wrong, it never looked exactly like him."
Kind of a bummer, but that's precisely why the FBI conjured up several more sketches as quickly as possible. For my money, I realize it was some 15-16 years later, I think the Unsolved Mysteries sketch is probably most accurate. Schaffner says "it's strong in my mind," and I have to believe her. This is not a witness who is drawing a blank, stammering and trying to remember details. The sketch also really reflect the hijackers age, which was speculated by all but one to be "middle aged", "mid-40s."
If we simply discount the only people who ever saw the SOB, what are we even doing here? Where do we start from? Do we start from a cleared suspect and then begin systemically discounting all the known facts that do not align with our suspect? In DB Cooper world, that seems by many to be the order of the day. The arrogance in just dismissing key eyewitnesses as being wrong based on zero evidence is always stunning to me. "oh, he didn't look like MY suspect? Plfft, what do they know, they're mistaken/wrong/incompetent and I know much better because I'm an amateur detective."