Never Trust a Leprechaun

Ron has been reading Roger Zelazny's The Chronicles of Amber to the kids each night before bed, and a few nights ago, they started whooping and yelling as he read. "You can't trust a leprechaun!" they yelled, "don't be so stupid!" The main character of the story, Corwin, had just gotten his horse stolen by a small man in a green suit, and he pursued him into a mountain and proceeded to sit down and have several drinks amid "hordes of meter-high people, red-faced and green clad, [who] were dancing to the music or quaffing what appeared to be mugs of ale." At one point Corwin even says "I knew the stories from another place, far, so far from here...to awaken in the morning, naked, in some field, all traces of this spot vanished...I knew, yet..."
Why is it that characters in stories never think these tales apply to them? Out of curiosity, after my kids' Rocky Horror Picture Show-like outburst, I looked at the fairy tale books they'd grown up with. Both kids agree that the stories they thought of immediately came from a little set of easy-to-read picture books entitled Leprechaun Tales that their grandparents brought them when they were very young. They have also read in Fairy Tales of Ireland (de Valera), English Fairy Tales (Jacobs), Grimm's, Andersen's, and eleven of the Lang fairy books of various colors. From these, the kids derived their ideas about the dangers of trusting fairies, little people, the Sidhe, etc. These are the rules, as Eleanor and Walker understand them:
Never trust a leprechaun. They always try to do the same things:
1. They party every night and if you disrupt the party, they'll lure you into a horrible trap.
2. You always have to be suspicious because they have magic powers and you don't know what kind.
3. Their time runs differently, so it could be 20 or 100 years before you emerge from their world.
4. They don't like humans and always try to trick them, usually with music, food, and drink.
5. They're possessive, especially of their land, flowers, and gold.
There are some truths we learn young, although few of us are able to put our knowledge to good use. As Corwin has some magic powers of his own, he and his horse escape from the leprechauns unscathed.