Did Sonny Liston cheat against ali?

It has never been proven Sonny Liston cheated. Sonny's corner claimed Ali's blindness was due to chemicals used to treat Liston's cut in the fight. However a boxing historian, Bert Sugar, found at least two other bouts of Liston's with similar occurrences. That in addition with Liston's street lifestyle and prior criminal record was enough to suggest Liston was involved in foul play in the view of many boxing critics.