Charlie, I can’t help thinking that the effect you note is a double-edged sword for Clinton: Yes, the average person catching a snippet of her Benghazi hearing in an airport might walk away with a reinforced belief in the Clintons’ shadiness, but that belief would likely be forgotten by the next news cycle, as one day’s crisis supplants another’s. Insofar as there are lots of stories demanding coverage at any one time, the consensus that Clinton knocked her hearing out of the park is a big political bonus, regardless of its truth: If the media thinks Benghazi is behind her, they’re going to cover it as if it is — which is to say, they’re going to cover it less. And the less they cover it, the more easily the average person will forget about it.
Now, if she’d actually been acquitted in a murder trial — in some alternate universe where murder charges don’t put an immediate, automatic end to presidential campaigns (which, come to think of it, might be the Clintons’ universe) — that’d be a different story. Even an acquittal would be unlikely to stanch the torrent of media coverage, and anyhow a murder trial is not so easily forgotten or dismissed as a byzantine scandal from three years ago.