Goofer Dust is a powder- and confetti-like substance used in hoodoo rituals. Its only known use in the Supernatural universe is as a ward against Hellhounds, similar to the way a line of salt works against demons.
A drawback of Goofer Dust is its nature as a powder. If not protected or maintained, a line of it can be broken or eroded by moving air—even that exhaled by the hounds themselves. Demons (for whom Hellhounds work) can also break the line, if the case may be. This makes Devil's Shoestring and rock salt better alternatives, given their weight—rock salt more so for its antagonistic effects against demons, Since that is a type of dust, if someone pours that in front of a Fairy, probably they have to stop to count each grain one by one.