Previously high-flying luxury brands turned downright ugly Thursday, falling faster than the broader market. Michael Kors (KORS) tumbled more than 7% Thursday, it's second-biggest daily decline since coming public in December. It closed at 50.70. Ralph Lauren (RL) plunged 3.6% to 150.30. Handbags and accessories maker Coach (COH) slid 5.3% to 53.91. Other apparel makers were hit, too. G-III (GIII), which makes Levi's, Guess and Kenneth Cole