In the 42 years I have worked for this newspaper, I have adopted many of this town’s mental habits. One is a deep respect for inspectors general, those stewards of truth whose work we often herald in The Post. That is why I am disappointed by the failure of not one, but two, inspectors general to expose test tampering in the D.C. schools.

From 2008 through 2010, according to testing company CTB/McGraw Hill, some D.C. schools had 70 percent or more of their classrooms flagged for wrong-to-right erasure rates far beyond the mean erasure rates for all D.C. students. When officials at those schools were denied after-hours access to the answer sheets because of tighter security, their test scores plummeted.

University of North Carolina professor Gregory Cizek investigated similar erasures in Atlanta. He found they were the results of cheating. Many culprits confessed and lost their jobs. Cizek and other psychometricians say there is no reasonable explanation for statistically improbable wrong-to-right erasures other than adults changing the wrong answers to right.

Such expertise apparently didn’t interest D.C. Inspector General Charles J. Willoughby and U.S. Department of Education Inspector General Kathleen S. Tighe. Their investigators found insufficient proof of massive cheating on the district’s standardized tests. It is easy to tell why, now that Tighe’s office has released a report on its findings and Willoughby has been forced by D.C. Council member Kenyan McDuffie to defend his work: Neither IG took the erasure data seriously.

They never studied the answer sheets. When test scores plummeted at Noyes Education Campus and other high-flying D.C. schools, it never occurred to the IGs to ask whether erasures also declined. Noyes educators blamed the declining scores on an influx of new students from low-performing schools. A computer check of enrollment rolls would have told the IGs whether that was true.

In his response to McDuffie, Willoughby also dismissed evidence from Adell Cothorne, a principal at Noyes Education Campus who reported suspicious behavior at her school. Cothorne said she found three staffers loyal to a former principal holed up in a room, after-hours, with answer sheets and erasers in their hands. She said she believed they were erasing wrong answers and penciling in the right ones on a D.C. preliminary exam.

Cothorne says Willoughby’s people never tried to interview her. Willoughby told McDuffie that Cothorne’s attorney said the principal didn’t want to talk. You decide who is telling the truth. The fact that Willoughby stopped his investigation after looking at just one school, Noyes, suggests little interest on his part in getting at the truth.

I congratulate Tighe’s staff for interviewing Cothorne in July 2011. The principal said they talked to her for several hours. Willoughby knew this but never mentioned it in his original August 2012 report. He said he couldn’t use her account because she had filed a whistleblower’s lawsuit against the District and the complaint had been sealed by the court – which happens in all whistleblower suits.

The Education Department also revealed Feb. 7 that several educators reported other forms and signs of cheating at Noyes and other D.C. schools: tests distributed days in advance to teachers who shared the questions with students; teachers coaching kids during the tests; kids excelling on the tests though they had performed poorly in class.

Yet both IGs apparently reject Cothorne’s assertions, though they don’t explain why. Because the three staffers she fingered denied any wrongdoing? Had they confessed, they almost certainly would have been fired. So why did the IGs believe them instead of her?

Cothorne now finds herself condemned as a liar after Schools Chancellor Kaya Henderson said she made “fictitious” claims.

Amid apparent lying, cheating and turning of blind eyes, I’d say that if there’s one honorable person in this five-year-long melodrama, it’s Cothorne. She’s the one who didn’t look the other way, instead putting her students’ interests first.