If there’s one really destructive myth this presidential election is feeding, it’s the idea that the world of politicians and their loyalists is divided into “the good guys” and “the bad guys.”

We know that most people are a combination. They have good days and bad days, smart plans and stupid ones, successes and failures. None of us could stand to be judged based on our worst day, and none of us deserves to be judged on our best one.

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But when it comes to Donald Trump and Hillary Clinton, and increasingly, our politics in general, such understanding goes out the window. They are snails and puppy dog tails. We are sugar and spice and everything nice. Any assertion to the contrary must be met with shouted denials and fingers stuffed in our ears as we sing “la la la la la.”

When this election is over, books will be written, plays staged, college courses designed and new mental illnesses diagnosed to describe all that happened. We’ll all be assigning blame for the ugliest political campaign since Stephen Douglas called Abraham Lincoln a “horrid-looking wretch, sooty and scoundrelly in aspect, a cross between the nutmeg dealer, the horse-swapper and the nightman.”

That used to be the norm, but in our lifetimes, we’ve mostly had respectful presidential races. So how did this all get so ugly? Who started it?

The voters did. Leaders can only take us where we’re willing to go, and many of us have been headed down a crass path.

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It was only eight years ago that Republican presidential nominee and Arizona Sen. John McCain forcefully stood up for his opponent, Barack Obama, when two questioners at a rally attacked him. To one man’s assertion that the idea of an Obama presidency scared him, McCain answered “I have to tell you, Senator Obama is a decent person and a person you don’t have to be scared of as president of the United States.” A few moments later, a woman told McCain she had heard Obama was “an Arab” and McCain took her microphone to answer, “No, ma’am. He’s a decent family man, citizen, that I just happen to have disagreements with on fundamental issues and that’s what this campaign’s all about. He’s not.”

McCain was heartily booed by the crowd for those defenses of Obama. But the right move is to revere him for it, even as we know McCain has made mistakes alongside his good deeds.

Clinton has a fine record of public service, but her hands are filthy with the cynical behaviors and personal enrichment of politics as usual.

Trump is a magnetic, dynamic marketer who is a genius at attracting followers and money, and who seems to either not understand what it would take to run the country or not be willing to be honest with his supporters about it.

A Trump supporter, left, plugs his ears while passing protesters waving signs and chanting against Republican presidential candidate Donald Trump, as Trump supporters filtered into the venue of a Trump rally at the Wings Over the Rockies Air & Space Museum, in Denver, Friday, July 29, 2016. Photo Credit: AP / Brennan Linsley

If you make a list of Clinton’s faults and contrast it with Trump’s strengths, you get a clear argument that she’s the devil and only he can save us. If you make a list of Trump’s faults and contrast it with Clinton’s strengths you get a clear argument that he’s the devil and only she can save us.

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But if you make a comprehensive list of the strengths and faults of both of them, the only clear argument is that in a democracy, people end up with the leaders they deserve. There is something wrong with this nation of late, wrong with this hatred and contempt we have for each other, with our love of the shallow and the judgmental, with our ever-crasser entertainments and illogical beliefs and self-centered views.

Clinton and Trump are just the mirrors. What they’re showing us and responding to is our hateful treatment of each other.

Our leaders will get better when we do.

Lane Filler is a member of Newsday’s editorial board.