When an individual or agency gains the reputation of being pure, or insists they are, they are the perfect cover for corruption.
Freakonomics found this to be true in the honored tradition of Sumo Wrestling, and in the public schools, which have had numerous reports of teachers fixing grades to improve the performance of school districts, for Federal funding dollars.
In any group of people, depending somewhat on the group and culture, you are likely to find 1 in 10 who purposely take what they want, whether through stealing, corruption, etc. You are likely to find another 1 in that 10 who can be pushed to do something illegal or unethical. And there are those who believe that everyone is dishonest about something and everyone can be bought - what is your price?
Even in religion, the prophets of Ancient Israel found the priests hiding a lot of indecent things. In Catholicism's history, the leaders, and even the pope were found to be corrupted in various ages. The leaders of today's churches are often found to betray their teachings and let down the public. You frequently hear of treasurers pilfering or leaving with the donations.
I like to say that nearly every leader will at some time do something to betray the public or harm his reputation, because all leaders are human and imperfect. We should not put them on pedestals - it just sets them up for a fall in our minds.
The police set up vulnerable people to convict for crimes to get the public off their back, scientists falsify statistical results to continue doing research, schools artificially inflate test scores, students cheat on tests, politicians do things for money, sports players use enhancement drugs and teams sweep negative things under the carpet, companies dodge taxes and hide financial results from investors, and just about every element in society have been shown at one time or another for individuals to be corrupt, or leaders to be corrupt, or for the entire organization to be corrupt.
It isn't unusual for entire organizations, which appear to be honored and above corruption, to be corrupt - a culture of corruption that is self-serving.
Thankfully we can usually trust 8 of 10 people.
We tolerate a certain level of corruption. We forgive and forget. Sports teams continue. Students continue cheating, and graduate, even though it means they didn't learn their coursework and probably do the same for whoever they work for. Politicians who have been accused of corruption, are sometimes returned to office simply because they are effective at gaining something their constituents want.
As a society, we have to be aware that corruption regularly occurs, there is a significant percentage of people in all fields who do it, and maintain safeguards to prevent it.
This is the role of monitoring groups, such as internal affairs in police departments, and other watchdog agencies who monitor congress.
Congressmen are often very powerful and determined to manipulate things to get their way. One of the things they do is either not fund government agencies that are set up to monitor, or reduce their funding so they can't operate effectively, or simply give them no powers to affect change. It takes the teeth out of agencies that are set up to protect the public. For example, if you don't want certain companies to have to abide by environmental laws, you simply cripple the agency that monitors them.
What I have found is that companies have cultures, and if you find mistreatment, making poor products, being dishonest - there is a good chance the entire company is that way and won't change. It stems from leaders choosing people who are like themselves, creating a culture that can't or won't change.
Congress loves to do things for show. They make a grand gesture of doing things for the public, and then not fund the programs, or not allow approval of administrators to come to a vote, or not allow votes on issues to come to the floor. It's basic deception and dishonesty. It's a major reason why the two major parties need to be in the minority.
If people know you are going to hold them to a high standard, and check and verify, they perform more honestly.
Trust but verify. Especially Congress, where there is much to gain in power, ideology, and money, by being disingenuous and dishonest, and a culture of deceit.