It definitely is not wise to doubt the existence of fairies- and to voice that disbelief too loudly or too forcefully. Here are a few examples of your likely fate if you do.
Disbelief in the face of tangible proof of the faeries’ existence and capabilities is especially hated by them. Very common are stories of humans who win faery favour by mending their broken tools, and a regular element in these is the companion who doubts and mocks any such assistance. In a Sussex version of the story of the ‘broken peel,’ a ploughman mends the baking implement but his mate scorns the whole idea- and dies a year to the day later. In alternative versions, a gift of food is given in return for the repair and the companion refuses to eat it- and suffers as a result.
Death may seem a disproportionate response, but it’s not unusual. A Shetland girl who had spoken lightly of the trows one night was drowned as she travelled home; a West Yorkshire man who mocked the boggarts instantly collapsed and died of a heart attack at Lumbutts, near Todmorden.
The Leeds Mercury for May 13th 1852 carried the story of an unbelieving butcher who was met one night by two female goblins. One jumped up behind him on his horse and the other ran alongside as he cantered. He was so terrified by the experience that, as soon as he made it home, he went to bed and expired. Another sceptic went to a well-known haunt of a boggart and called out mockingly, asking where it was. It replied that it would be with him shortly, once its shoe had been tied and, before he had a chance to think better of things and flee, it jumped out, grabbed him, and dragged him through bogs and briars until his clothes and skin were shredded and the pound of candles he had had in his pocket were reduced to the wicks alone. He was left in a ditch, barely more alive than dead.
The pixies of the South West of Britain seem to be especially touchy about doubters and there are several stories of people punished by them for scepticism- usually by pixy-leading them.
In William Bottrell’s story of Uter Bosence and the Piskey, the man is drunkenly making his way home one night. He has laughed at stories of pixies and is regarded by other local people as an “unbelieving heathen” as a result. A fog arises and he becomes trapped in a field, unable to find the way out. Uter decides to rest in a ruined chapel until the weather improves or dawn comes, but instead, he is confronted with a band of spriggans and a terrible goat-like being with blazing eyes and paws instead of hooves, which tries to dance with him. Then he’s knocked over and dragged across the moor- an experience from which he never fully recovers.
A Somerset man returning from the pub found himself misled and lost because he had sneered at the possibility of pixies. He was rescued by a local farmer who heard his cries of distress and, in response to the experience, the man worked on his saviour’s farm for free, saying that he did this to please the pixies, so that they wouldn’t give him a “gude lammin’” the next time they came across him alone at night.
In Enys Tregarthen’s 1940 story, Why Jan Pendogget Changed His Mind, the main character is another disbeliever who unwisely is too vocal about his contempt for such childish ideas as pixies. He attends St Columb fair one day- and his mother advises him to avoid crossing Undertown Meadow on his way home because the pisky folk have been making rings there. He ignores this, of course, and is pixy-led. He can’t find the gate out of the field and then can’t locate the one he entered by either. He sees lights bobbing and hears the pixies laughing- and is trapped all night until dawn.
Cornish miner called Tom Trevorrow doubted the existence of the knockers in mines. He refused to share his food with them and ignored the warnings of their displeasure at his disrespect (falls of stones in the workings), so finally they caused a roof collapse that buried the lode he had been working, along with all his tools.
One of the least violent of these types of tale may be the Dartmoor story of Nanny Norrish, whose scepticism is answered one night when she meets the pixies piled up before her in a pyramid and all chattering loudly. Nanny appears to have got off lightly, considering what we’ve already seen and given that another Devon folklorist averred that the pixies’ “malevolence will know no end” towards one who’s spoken ill of them.