Seeing that the Beatles pretty much always played through ultra clean amps (Vox AC-30's, Fender Twins, etc.) they held their own better than most would under the circumstances. They used no distortion pedals, no Marshall amp distortion, just out there naked, piercing clean, nothing to hide behind. Even in the studio they pretty much played clean. Revolution was one exception and I'm sure there are others but not many. Distortion hides many a mistake.