MADRID -- When King Juan Carlos appeared at a recent basketball game in front of thousands of subjects, he was greeted by persistent heckling and whistling. It was an unprecedented spectacle in a nearly four-decade reign over which the monarch has basked in the nation's love and respect.What happened? The immediate cause is a corruption scandal engulfing Juan Carlos' son-in-law, Inaki Urdangarin, which has angered Spaniards in a time of crushing austerity.