Barmecide
adjective
[ ˈbɑːmɪsʌɪd ]
• illusory or imaginary and therefore disappointing.
Barmecide
noun
• a person who offers benefits that are illusory or disappointing.
Origin:
early 18th century (as a noun): from Arabic Barmakī, the name of a prince in the Arabian Nights' Entertainments, who gave a beggar a feast consisting of ornate but empty dishes.