Barmecide

Barmecide, also Barmecidal, is a state of being disappointing on account of its being illusory or imaginary. Therefore, someone who offers benefits that are illusory or disappointing. This term is derived from the Arabic Barmaki, the name of a prince who figures in a story of Alph Laila Wa Laila (Thousand Nights and One Night), more popularly known as the Arabian Nights. He gave a beggar a feast consisting of ornate but empty dishes. It is from that story, the word came to mean utterly disappointing empty offer.