His political nemesis, Mayor Bill de Blasio, is destined to be haunted by one Harendra Singh, a restaurant owner who, it was recently reported, secretly pleaded guilty to bribing Mr. de Blasio in return for help getting favorable lease terms. No charges were brought against the mayor or his aides. Federal prosecutors noted last year that making a case would have been difficult, presumably because the United States Supreme Court had raised the bar for proving political corruption months before Mr. Singh’s plea in 2016.

Nonetheless, the specter of shadowy behavior isn’t going away, not with Mr. Singh figuring in another federal corruption trial about to begin, that of Edward Mangano, a former Nassau County executive. He’s accused of taking Singh bribes. Mr. Mangano’s lawyers have left little doubt that they will make Mr. Singh’s de Blasio connection — and the absence of any charges against the mayor — part of a strategy to discredit him as a prosecution witness.

For Mr. Cuomo, who’s up for re-election this year, discomfiting proximity to criminal cases does not end with the Percoco trial. Another administration insider, Alain Kaloyeros, has his own federal court date in May. Dr. Kaloyeros, who headed the State University of New York Polytechnic Institute, is charged with corruption in connection with pay-to-play projects upstate.

Courthouses aside, the governor has trouble keeping his deeds fully in sync with his words on ethics. He has repeatedly urged the Legislature to close the “L.L.C. loophole,” by which corporate interests pump vast sums into political campaigns through a series of limited liability companies. No action has been taken, a failure arguably more on lawmakers than on Mr. Cuomo. But having claimed the high ground, he could show seriousness of purpose by not slipping through that loophole himself. Instead, he has used it to plow many hundreds of thousands of dollars from corporate donors into a campaign strongbox containing more than $30 million.

Similarly, he renewed an executive order imposed by a predecessor, Eliot Spitzer, under which most people in state positions are forbidden to donate to, or solicit political donations for, the governor who appointed them. But Mr. Cuomo and his counsel interpret the order as applying solely to those who can be fired by the governor at any moment. It doesn’t cover people who’ve had legislative confirmation and serve fixed terms, they say. That smacks of pettifoggery. A Times investigation disclosed this week that 37 Cuomo appointees contributed a total of $2.2 million to his political campaign, directly or through relatives and companies they own or control.