David Marsh under the heading A factoid is not a small fact. Fact. Norman Mailer, widely credited with coining the word in his 1973 biography of Marilyn Monroe, said that factoids were "facts which have no existence before appearing in a magazine or newspaper".
Here are a couple of quotes:
Books about grammar and language are full of factoids, such as George Bernard Shaw spelling "fish" as "ghoti" and Winston Churchill writing "this is something up with which I will not put". I think the writers want these stories to be true, so repeat them, even when there is little or no evidence for them.
Part of the Mailer definition that is usually overlooked is that the media create factoids not so much as lies but "as a product to manipulate emotion in the Silent Majority"