Disdain is the common wisdom among foreign institutional investors toward Chinas B shares. Those who sold too early and missed the past months rally may rue their hastiness, but overall the market is too volatile and the companies too shoddy to stir much interest. It would be pointless to now try to chase the rally, which has more than doubled the market capitalization of the Shanghai and Shenzhen stock exchanges from $18 billion to $42 billion in...