I guess the problem is that we've been burned so often, that the rumours have proven to be true so often, the suspicion proven well founded, that it feels naive to want these rumours, these questions, this time, not to be true.
In cycling, all the whistle blowers, who were widely disbelieved at first, have proved to have been telling the truth. It stretches credulity to think Salazar is clean - and his reaction to the allegations has echoes of Armstrong, namely smear the accusers, accuse them of agendas. Are they all lying? I very much doubt it. Yet he's still Farah's coach. At best that's poor judgement.