Writing at the Daily Dot, EJ Dickson confesses to perpetrating a fraud: planting a false entry in Wikipedia about the Amelia Bedelia children's books saying that the character is based on a maid in Cameroon.
She was, she concedes, stoned at the time and now is horrified to discover that her little lark has become so widespread that it is believed by the nephew of the late author of the Amelia Bedelia books. 
She consults a Wikipedia editor, who explains that "subtle vandalism" is unlikely to be detected because it doesn't look outrageous and there is no "systematic review system" on Wikipedia. 
Here is the salient passage: "Ultimately, what I learned from my inadvertent Wikipedia hoax was not that Wikipedia itself isn’t reliable, but that so many people believe it is. My lie—because that’s what it was, really—was repeated by dozens of sources, from bloggers to academics to journalists. They knew better than to attribute Wikipedia directly, because even a seventh-grader knows citing Wikipedia as a source is tantamount to admitting that you haven’t done any research at all. Instead, they referred to the source of the Amelia Bedelia Cameroon lie in vague terms, such as 'the literature I've read' on the subject. ..."
So we find laziness combined with gullibility, and the combination is hardly novel. 
Jonathan Swift wrote in a letter to Alexander Pope of an Irish bishop who read Gulliver's Travels, concluding that it was "full of improbable lies, and for his part, he hardly believed a word of it."*
In the early years of the Republic, newspapers were so recklessly partsian that they published lies and slanders that would make Fox News blush, all for an audience marked by the will to believe.
In 1917, H.L. Mencken published in New York's Evening Mail a bogus history of the bathtub, a spoof. Nine years later, writing in the Chicago Tribune, he described how his innocent hoax had penetrated into lore and literature:
"I began to encounter my preposterous 'facts' in the writings of other men. They began to be used by chiropractors and other such quacks as evidence of the stupidity of medical men. They began to be cited by medical men as proof of the progress of public hygiene. They got into learned journals. They were alluded to on the floor of congress. They crossed the ocean, and were discussed solemnly in England and on the continent. Finally, I began to find them in standard works of reference. Today, I believe, they are accepted as gospel everywhere on earth. To question them becomes as hazardous as to question the Norman invasion."
People know, or ought to know, that those supermarket tabloids are given to invention. People know, or ought to know, that Wikipedia is neither authoritative nor reliable. People know, or ought to know, the proverb that a lie is halfway around the world before truth has got its boots on.
But people, by whom I include pretty much all of us, tend to be credulous, especially about what we are predisposed to believe, and usually too lazy to check. 
*It would not strain credulity to suspect that Swift may have invented his Irish bishop.