The links i provided describe the mechanism in greater detail. Those articles are a great reference. Usually i avoid getting into a situation where a trashed reputation becomes relevant, thus i cannot offer comprehensive first hand experience. With 500 shields it is the most expensive wonder of the ancient age. Using a Great Scientific Leader for it may be convenient. But else it seem a lot wiser to build 17 horsemen for those shields and conquer cities, possible containing that wonder. At emperor and above AI tend to finish wonders in a timely fashion. It is somewhat helpful if AI wastes 500 shields for that wonder instead of building an army worth of 500 shields instead.