This article is from the The Simpsons FAQ, by Ondre Lombard wakkojr@nospam.wcat.com and Andrew Gill superluser@mail.rit.edu with numerous contributions by others.
Smithers did appear to be black in one episode (Homer's Odyssey). He
was not, though. It was a coloring error. If you look at it, it's sort
of an off-black, somewhat akin to "a Caribbean sunburn."
 
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