Thomas Edison conducted thousands of failed experiments before the light bulb.
No doubts he was labled a moron 
According to Rutgers, Myth Buster: Edison's 10,000 attempts, "The source of the story about Edison trying thousands of experiments or materials is probably an 1890 interview in Harper's Monthly Magazine."
The exact quote by Edison:
"I speak without exaggeration when I say that I have constructed three thousand different theories in connection with the electric light, each one of them reasonable and apparently to be true. Yet only in two cases did my experiments prove the truth of my theory. My chief difficulty, as perhaps you know, was in constructing the carbon filament, the incandescence of which is the source of the light."
The Rutgers article also describes another quote by Edison in a 1910 biography as it relates to Edison's later work on storage batteries.
The book quotes Edison's friend and associate Walter S. Mallory:
"I said: 'Isn't it a shame that with the tremendous amount of work you have done you haven't been able to get any results?' Edison turned on me like a flash, and with a smile replied: 'Results! Why, man, I have gotten lots of results! I know several thousand things that won't work!'"
The Thomas A. Edison Papers of Rutgers University is probably the most reliable source of information on Thomas Edison.
. . . . . . and Mad Mike has a result, he knows what doesn't work
