Fairy dust? I would not recommend you look up the meaning of this phrase on Urban Dictionary, an online resource for slang. Slang meanings often have no relation to the original intent of the speaker.
For example, I doubt the Republican gentleman who commented last evening that President Obama’s State of the Union address was nothing more than fairy dust meant for anyone to go beyond the denotative meaning to the less conventional and overtly nasty connotative meanings available at large.
Nevertheless, before using such a phrase to describe our president’s speech before the nation, an intelligent person might explore all the meanings attached to that phrase — especially since “fairy dust” is not a common description of State of the Union addresses.
Now, I realize the temptation to look up fairy dust in the Urban Dictionary is strong. Resist — the phrase as slang poisons the mind and depresses the heart.