IGs are a very necessary evil.
My experience with inspectors general stems from my time in the United States Army. One of their major functions in the military was to do inspections of military units, typically at the battalion level (that would be about 800-1,000 people) with subordinate units called companies with around 130 people.
These IG inspections would occur perhaps annually, or at least semi-annually. I've been in units that passed inspections with flying colors and in a unit that failed the inspection, with the removal of the commanding officer coming after that failure. IG inspections were "BIG Deals."
Most of these inspections were announced in advance so there was time to prepare. However, I went through two no-notice IG inspections. Serving in armored divisions, maintenance was always key. There was an old saying, "There are two glass balls. One is maintenance and the other training." This was not true, the only real glass ball in an armored division was maintenance. If your mission is to "move and shoot" and you can't move, then you "can't shoot either."
I remember one in-briefing at the start of an announced inspection. The head of the IG team stood up said the one big lie to our coming is when we stand up, like today and say, "We are glad to be here, and you in return then say, "We are happy to have you here." These were pucker factor inspections for the inspectees.
Which is all background which brings me to the firing of inspectors general in the Trump administration by the president. See this Daily Podcast intro and link:
Trump’s Purge of the Watchdogs: It used to be rare for a president to fire an inspector general, a position created within government agencies after Watergate and assigned to fight waste and corruption. Today, we look at what President Trump’s pattern of replacing inspectors general reveals about the nature of the independent office — and about presidential power. Guest: Maggie Haberman, who covers the White House for The New York Times. For more information, see this link to listen to The Daily Podcast.
Here's the deal. The IG function is not to find everything that is going right. They are there to find things that need improvement. The IG will never go away saying "everything is wonderful" because it never is. They are inevitably, by their very function, if they are doing their jobs, the bearer of bad news. In today's vernacular for some, "fake news" because it is bad. Favorable polls are good. Bad polls are fake. You get the picture!
IGs are adversarial by design. If you are looking for a pat on the back, don't have the IG come visit.
The other significant function of the IG is to root out corruption in government. I recall someone who had been an IG at the Pentagon who as a full colonel who did investigations of general officers. That's right, general officers. He told me of on incident where a general officer told his personal aide de camp to take the hardware off the drawers of the room he was staying in at a hotel, because he wanted to use them at home. That is the kind of behavior that leads to "early retirement."
I don't know if I'll ever get to say, "Glad to have you here" to an IG in my lifetime, but if I should experience it, I consider it part of the accountability process that keeps us strong and honest as a nation.