Doping scandals have cast a shadow over the Olympics for decades, and many top American athletes say they assume at least some competitors are dirty.
But this has been a particularly bleak year, with Russia accused of running a state-sponsored system to help athletes evade drug testers at the 2012 Summer Games in London and the 2014 Winter Games in Sochi.
The international governing body for track and field banned Russian competitors from Rio, but Olympic leaders recently rejected calls by anti-doping officials for a complete ban on Russia and gave individual sports federations the task of deciding which athletes should be cleared. As of publication, five other Russian teams had been partially banned.
Meanwhile, the World Anti-Doping Agency just recently approved lifting the provisional suspension of accreditation for the Rio lab charged with analyzing athlete samples for the Olympics.
So if the sky isn't falling, it's at least creaking.