Misguids are some sort of folkloric creature mentioned by the villagers of Upper Posada in the short story "The Edge of the World". They are mentioned along with mamunes and described essentially as pests. Certainly Geralt feels no need to hunt them down.
|“||...misguids and mamunes, which prevent an honest peasant from finding his way home in a drunken stupour...||”|
— pg(s). 165, The Last Wish (UK edition)