Despite the chemical bath origin being widely applied to explain the genetics behind the Joker's permanently bleached skin, there are still rumors and speculation amongst fans that the Joker never actually fell into the acid bath.
Many claim that it is just one possible scenario, while other scenarios have yet to be explored. Shortly after creating the Joker, a close friend to Bill Finger revealed that the Joker's parent considered one particular origin, other than the chemical bath origin. Apparently, Bill Finger was prepared to write a story on how the Joker was involved in a major chemistry accident as opposed to the "Man Behind The Red Hood" story arc. Finger originally pulled out of writing a Joker origin story because he found that the greatest aspect of the Joker was the amount of mystery surrounding the character.
To this day, various writers have considered re-telling the Joker's origin, but have found that it is a widely accepted truth that the Joker fell into the acid bath while donning the Red Hood costume. However, the exact nature of the Joker character has yet to be fully realized, according to those who worked closely with Bill Finger and Bob Kane. After the release of "The Man Behind The Red Hood", Bill Finger publicly stated that his story serves only to generate speculation as to how the Joker became permanently bleached. Furthermore, the Joker parent claimed that "The Man Behind The Red Hood" was presented as a narrative-type story, being deceptively told by the Clown Prince of Crime.
In 1988, Alan Moore released "Batman: The Killing Joke" - a story that has been hailed as the greatest Batman story of all time. Alan Moore insists that "The Killing Joke" was climatically inspired by the comments made by Bill Finger after the release of "The Man Behind The Red Hood."
"I studied the Joker a lot - especially the Red Hood story arc. I found that it was a pretty accurate origin for the Joker, but at the same time it was highly deceptive. If there is one thing that I could say to a Batman comic-book reader, it would be to never trust a Joker story."
~ Alan Moore, The Torment Magazine, 1989