But let’s not be partisan here. Recall that other time Jon Stewart ridiculed John Kerry’s smile.

Come to think of it … it seems to happen rather a lot of the time. As Megan McArdle has well put it, “If you want an election where no one makes fun of their opponents, run for kindergarten class president.”

It’s a pretty notorious fact about politicians that they are seldom sincerely happy to share a stage with their opponents. Hillary Clinton has sometimes seemed even less happy than most.

So when she opened her mouth in a wide recurring “I’m just so delighted to be here”-grin through most of the first 20 minutes of her Hofstra University encounter with Donald Trump, it would have been a very credulous person indeed who imagined her sincere. Especially since the smile quickly dropped away.

When I posted my tweet at 9:31 p.m., I fretted a little that I might be offering too glaringly obvious an observation. It was obvious, but it stood largely alone, because a waiting Twitter platoon had been battling for some weeks beforehand to label any comment on Hillary Clinton’s facial expression as an intolerable affront. Support for women's equality, they suggest without apparent irony, requires holding women politicians to a different standard than men.

Not all women qualify for the protective treatment, however. There’s a lively online library of abuse of Sarah Palin’s smile on Democratic-leaning websites. And of Michele Bachmann’s. Even of Ann Romney, who didn’t run for office herself.

On closer inspection, in fact, the “no criticizing the smile” rule looks more like a special one-off exemption available to Hillary Clinton alone. I pulled up all the above examples either from memory or on the Google machine between conference sessions in far-away Estonia. No writing staff! I have to imagine that the members of Bee’s professional team could have unearthed 50 more examples had they cared to look—or to test their own unreflecting ideological certainties and party loyalties.

Modern late-night comedy has long ago laid aside its one-time goal of “making you laugh” for a new, less-ambitious hope of “making you think.”

But you can’t inspire others to think (as opposed to merely clapping and repeating) unless you do some hard thinking yourself first.

If it’s OK in certain cases to mock the political smiles of men, but not of women (or anyway, not of Hillary Clinton—Michele Bachmann and Sarah Palin seem not to count for these purposes), which are those cases?

Unquestionably, Hillary Clinton (and other female politicians too) face forms of abuse that their male counterparts do not face. I photographed this T-shirt at the Republican convention in Cleveland:

You couldn’t do that image the other way around.