New Yorkers pride themselves on being sharp and sophisticated, and often they are. But sometimes their self-image blinds them to an obvious rip-off. How else to explain their silent acceptance of a no-show mayor?

In a vigilant city, The Post’s report that Mayor Bill de Blasio appeared at his City Hall office for just seven hours — yes, seven hours! — in May would send shock waves through the civic arteries. Business, educational and political leaders would be denouncing the blatant dereliction of duty and the dangerous signal it sends to other municipal workers.

Good-government groups, which used to be a potent force, would be furious, noting that seven hours is not even a full day’s work. They would demand to know how de Blasio could possibly think he could travel the country in a fool’s quest for the presidency and still manage the largest city in America, with a budget of $92.2 billion and more than 300,000 employees.

They would point to previous mayors who met with their staffs and attended public events on a near-daily basis, and demand that de Blasio get back to work.

Activists and residents would blast the lack of mayoral attention for the vexing problems of homelessness, traffic congestion and other municipal failures. Angry taxpayers would converge on City Hall to demand a refund.

They could point out that they are paying the mayor a pretty penny of $258,750 a year, which works out to more than $21,500 a month. Throw in free housing for his family at Gracie Mansion and those footing the bill could rightly say that de Blasio is living large on the public dole — but not doing his job.

In short, the outrage would be so widespread that de Blasio would be forced to get his act together, or at least pretend to. He would hold a press conference to say May was an aberration because he was ramping up his campaign and promise he would not forget the pact he made with residents when he twice sought, and got, their votes.

All that and more would happen in a city that holds its leaders accountable and expects them to give their time and best efforts to making it better and safer. New York used to be that kind of city, but no more.

Faced with proof its mayor no longer cares about his day job, the city shrugs its collective shoulders and gives de Blasio a pass, with the lack of public outrage the enabling element that makes his scam possible.

But where are the comptroller, the City Council, the borough presidents? Shouldn’t the public advocate actually advocate for the public and demand that the mayor do his job or give it up?

Yet top city officials are all silent, in part because so many of them plan to run for mayor in 2021 and are afraid of scaring off de Blasio supporters. Add their refusal to hold the mayor accountable as another black mark against New York.

In reality, the seven hours de Blasio spent at City Hall in May will be something of a high-water mark. Since then, he has been spending huge amounts of time traveling to and from the early 2020 states of Iowa, New Hampshire, South Carolina and Nevada.

That he couldn’t even qualify for next week’s debate only compounds his offense against New York. As I noted, he’s neglecting the best job he’ll ever have in a bid for a job he’ll never get.

The only issues he cares about are those he can point to on the national stage. Recall that the death of Eric Garner five years ago became a hot topic at a July debate, and de Blasio was put on defense over the fact that the officer involved, Daniel Panteleo, was still a cop.

So it is no coincidence that NYPD Commissioner James O’Neill reportedly spoke to de Blasio just before recently deciding to fire Panteleo. Although de Blasio’s office insisted that only O’Neill had the power make the decision, bet your bottom dollar that the mayor will boast about the firing to national Democrats, essentially taking credit for it.

Ditto for his insane plan to quash merit selections in the city school system. It makes zero sense to anyone who knows anything about the racial reality of schools, but the mayor will sell the plan as proof that he is committed to the far-left agenda of declaring individual achievement a vestige of white privilege.

In these and other ways, de Blasio has spurned his responsibility to do what is best for the city and done only things he believes will help him nationally.

And New York shrugs, proving once again that we really do get the government we deserve.

China prefers Don to anti-biz Liz

President Trump’s warning to China that he would double the pressure in a second term reflects his conclusion that Beijing is stalling on trade talks because it believes it would get more favorable terms from a Democrat in the White House.

I agree, and assumed that China would wait until after the election and even try to help elect a Dem.

Not so fast, says a friend wise in the ways of politics and global finance. He believes Chinese leaders, for all their tough talk about Trump, would prefer the incumbent to any of the far-left Democrats, especially the leader of the group, Sen. Elizabeth Warren.

The reasons are the same ones that scare many Americans about Warren. As my friend puts it, the Chinese look at Warren’s policies and see a disaster for their economy, as well as ours.

Take her attack on large corporations. Many are multinationals, and the punitive changes Warren is pushing on their governance and tax structures would almost certainly damage their bottom lines.

In this case, what’s bad for America would be bad for China. A fall in corporate earnings would mean a fall in stock markets in both the West and Asia.

Those same companies operate in the European Union, which is also a major trading partner with China. Slower economic growth there would further stress weak EU banks and add to China’s domestic woes.

None of this is to suggest China will make a quick deal with Trump. More likely, it means there will be no deal before the election, and maybe none after it either.