"an off-white white elephant"

A white elephant is an idiom for a valuable but burdensome possession of which its owner cannot dispose and for which the cost of upkeep is greater than its usefulness or value.  The term derives from the story that the kings of Siam would present a sacred white elephant to courtiers who had rendered themselves obnoxious. The recipient would soon be financially ruined by the cost of maintaining the animal, which had to be treated with great respect.  In modern usage, a white elephant is usually an object or building considered to be without use or value.