Look at the consistency of their performances and look at who they associate with.
This isn't the 1970s, 80s or 90s anymore, or even 2002 when these BALCO assholes were getting away with murder. The Greeks aren't making their usual two out-of-nowhere performances anymore, Graham and Remy are out of the sport and Stambolova and the Bulgarian/Belarussian cheats are getting nailed. This is probably the cleanest our sport has ever been (certainly in the testing era).
Some haven't been hit yet. Ramzi still has his Helsinki golds (what a load of shit that was!) and Nesterenko quickly went back into oblivion. You'll notice that some of Graham's other former runners that never tested positive came back down to Earth after the Gatlin bust and his de facto blacklisting. Expect them to stay there, if they're smart. Unless there's some BALCO-like revelation/scandal, they'll probably keep their stolen hardware, but we can hope that they don't get to collect anymore.