NEW YORK — Frank Luntz, the Republican political consultant, is a master of the political epigram. Under his tutelage the estate tax became the death tax and global warming became climate change. So Luntz, once again going to the heart of the matter, recently put an either-or question to a group of about 50 people: What would you rather see, Donald Trump’s taxes or Hillary Clinton’s emails? Upon that question hinges the election.

Luntz was speaking to an invitation-only gathering in the Hamptons. There was only one acknowledged Trump supporter in the room, yet when Luntz called for a show of hands, most of them went up for Clinton’s emails.

Luntz conducted his mini-survey more than a week ago. Had he done so after Clinton had collapsed at the September 11 memorial service in New York, the numbers would have been higher. Here, in a single episode, were the Good Hillary and the Bad Hillary in a gripping and worrisome relief. The Good Hillary is the woman who shows up — no matter what. She is dutiful and responsible and determined not to be the woman Trump says she is — too frail for the physical challenges of the presidency. She would rather collapse than not attend the memorial service.

And yet the Bad Hillary is here, too, the one whose opaqueness is so troubling. She was diagnosed with pneumonia on Friday, yet she said nothing about it to her traveling press corps. On Sunday, she was forced to leave the commemoration ceremony and had trouble getting into her SUV. From the video, she seemed to buckle, her legs going wobbly, and she had to be lifted under her arms into the vehicle. The press corps was again not informed of what happened. Clinton was taken to her daughter’s apartment where, among other things, she was rehydrated. When she emerged two hours later, she looked fine. She waved to the crowd. “I’m feeling great,” she said. “It’s a beautiful day in New York.”

No! First of all, it was not a beautiful day. It was cloyingly humid. Second, while I am in no position to say she was not “feeling great,” I have had pneumonia myself, and it sure took me a while to get back to normal. Clinton had been diagnosed on Friday. This was Sunday.

Instead of issuing some anodyne statement, Clinton should have said what had happened — and how she actually felt. At the same time, she should have said that she so much wanted to honor the victims of the terrorist attacks that she attended the ceremony against her doctor’s orders. That would have been commendable, even a bit heroic. Instead, she turned the incident into yet another issue about transparency.

The paradox of Trump is that greater transparency will not teach us anything. There is nothing to learn from Trump’s taxes. It is a given that he pays very little, that he has donated next to nothing to charity and that he has reneged on his pledges. He is worth less than he claims, but so what? He is as he appears, a flamboyantly tanned liar. The mystery is not Donald Trump. The mystery is the people who support him.

Luntz asked about Clinton’s use of a personal server for her emails. By itself this is a mere piffle. Historians of the future will be baffled by what a to-do we’ve made of it and how we’ve allowed an epic liar such as Trump to constantly accuse her of committing a crime. What crime? Is it similar to the one Colin Powell committed when he was secretary of state and used a personal email account for government business? Apparently not. I don’t hear Rep. Jason Chaffetz, the chairman of what amounts to the Permanent Special Committee to Harass Hillary Clinton, vowing to go after Powell, as he has Clinton.

The notion that we somehow earn our diseases causes us to look for the chink in someone’s armor to explain their death — ah, he smoked, ah, he was overweight, etc. In Hillary Clinton’s case, the “illness” is transparency. It could prove politically fatal.

Richard Cohen is a columnist with The Washington Post. His email address is: cohenr@washpost.com.