Fairies are often portrayed in folklore as the guardians and bestowers of treasure. Many folktales warn against greed in seeking treasure from the fairies. In some cultures, there was even a deep-seated *fear* of finding treasure, with extreme measures required to get rid of it 
Fairy treasure, in most folk traditions, generally brings trouble. And in a more practical sense, the discovery of treasure is economically and hierarchically disruptive. It may seem strange, but some people lived in fear that fairies would make them suddenly wealthy
In Lithuanian folklore, for example, there is a rite for dealing with a fairy (aitvaras) who turns up to give you treasure. The aitvaras will depart, and take his treasure with him, if you bare your buttocks
If you don't manage to drive the aitvaras away by mooning at him, however, something more drastic is required to get rid of the treasure he leaves with you. You must leave it at the crossroads and defecate on it
All of this scatological folklore is not without meaning; human excrement, folklorically speaking, often functions as an opposite of gold - so if you want to get rid of fairy gold, excrement and the act of defecating are likely to play a part
It's interesting to speculate on why a culture would develop a fear, not only of the fairies who bestow treasure, but also of the treasure itself...
