This allows for great flexibility for an entrepreneurial player. Trading away those single luxuries may get you valuable Gold income when you need it, or allow you to get access to other luxuries, while still retaining sufficient Happiness.

This ability is quite powerful because a civilization rarely has more than one count of most luxuries (especially in the early-middle of the game). First, they have a unique ability to retain half the Happiness bonus of a luxury resource they control after they've traded their last copy of it. The Dutch, introduced in the Gods & Kings expansion for Civilization V, is an interesting civilization. Combine these bonuses with Petra, if possible, to create a fantastic dessert paradise city! Not only does the Bazaar give them additional Gold from oasis tiles (consider this when searching for places to found new cities), but the Oil resource also gives them double quantity, and Oil is usually abundant in deserts. The Arabians are also the best civilization to settle deserts (except obviously Morocco and situationally the Inca). Combine this with the Commerce policy tree to maximize land trade power. The Bazaar gives an additional copy of each luxury resource worked by the city, giving the Arabians much greater bargaining power, even in the early game. The Arabians are one of the best trading nations in the game - not only because of trade routes that produce additional Gold (in vanilla and Gods & Kings) or their extended Caravan range (in Brave New World) - but also because they gain access relatively early on to the Bazaar, a terrific unique replacement for the ordinary Market.

Civ 5 campaign edition vs civ 5