Fairies have a pretty good public image. They're widely regarded as good creatures, since they're small, delicate, and magical. But in European folklore, they were often considered quite malevolent. The wikipedia article on fairies
notes the belief in fairy kidnapping:
Any form of sudden death might stem from a fairy kidnapping, with the apparent corpse being a wooden stand-in with the appearance of the kidnapped person. Consumption (tuberculosis) was sometimes blamed on the fairies forcing young men and women to dance at revels every night, causing them to waste away from lack of rest. Fairies riding domestic animals, such as cows or pigs or ducks, could cause paralysis or mysterious illnesses.
And apparently, the belief in fairy kidnapping created an opportunity for con artists. Dr. Beachcombing, who runs Beachcombing's Bizarre History Blog, notes the existence of what he calls "fairy shysters"
Sharp swindlers who, in the nineteenth and twentieth century, went around taking innocent and usually vulnerable men and women for 'a ride'. Beach has gathered some remarkable examples together, including three extraordinary instances of 'fairy shysters' posing as fairy kidnapped family members.
Unfortunately, Dr. Beachcombing is holding off on describing these cases until a later date, but I thought the idea of a fairy shyster was intriguing.