Attending Art Basel used to feel like having membership in an exclusive club: Not many people knew about it, and the perks included an early entrance time to the V.I.P. preview, a stroll around the summer show at the Fondation Beyeler, a stock of envy-stoking tales from gallery dinners, and late nights at the bar of the Trois Rois. This year, while I’m told that the “exclusive” preview was packed, there was a notable absence of American and Asian collectors at the fair, and an uncomfortable feeling that the place was crawling with art advisors. Worse, the biggest-ticket items didn’t seem to be selling.