“Since Thomas Krens took over in 1988, the air around art at the Guggenheim has been distorted and toxic. Yet since he left his directorship in 2005 to run the Guggenheim Foundation, which oversees all five museums (New York, Venice, Berlin, Bilbao, Las Vegas), the institution has shown auspicious signs of actually putting his tenure behind it. But something rotten is brewing. Krens has been up to his corrosive old tricks again.”