I wouldn't expect people to confess to me if I was investigating allegations against them.
That depends on the intention of the investigation. If the intention is to put me in prison, I would concur. If the intention is to determine why an accident, incident, or other trasgretion took place and to rectify the cause of that failure through preferably a bit of extra training, (could be delivered right there during the investigation interview or phone call) then I don't concur because the intent of the investigation reaching it's designed conclusion serves my best interest, and believe it or not, when you first start talking to an investigator, that is their intent. If you really screwed one up and the controller is terse with you at first, remember, you likely just cost them a bunch of paperwork they don't have time or desire for. "Sorry, I screwed up" goes a long way towards changing their attitude to a more favorable one.
In most situations where no one was injured, you're likely better off taking the blame fully on your shoulders even if you are only partially at fault or have reasonable defense. They EXPECT you to screw up every now and then. If you accept responsibility rather than try to reapportion it, they are seeing what they want to see.
IIRC on my gear up thread several people thought I had screwed myself and predicted doom and gloom. NOTHING could be further from the truth of how it went down. There was no one at any time that was anything less than helpful towards me. Even though they have 30 days to do a 709 or issue a suspension, since I put my cert on deposit with them, when they couldn't manage to get my 709 done due to internal problems, they sent my cert back to me because, "It wouldn't be fair to you for me to keep your cert if I can't give you the ride. It's fully valid, we'll give you a call when we can work something out."
The reason I was treated as I was I am certain is because I closed the investigation part with my first 3 words, "I ****ed up". With that he smiled, shook my hand and said, "Thanks for being honest." After that I reviewed all the circumstances and week long chain of events that lead up to the accident with him and the NTSB investigator as the plane was being jacked up. Everything was done except the 709 ride at that point, and he said he would try to get it scheduled that week. When that proved impossible, and I would be out of country for the next 2 months, they offered, "You can put your certificate on deposit with us and when you get back we schedule it, that way there is no suspension proceeding in your record." Now I've got the inspector and his boss looking out for my best interest.
This is typical of every experience I've had with the FAA. Heck, I crashed an Ag plane and when I went in to answer my letter from counsel and I reviewed it with her explaining the weather conditions and my error in not standing my ground on not flying until the system had moved through. She asked the Safety Counselor guy there, "Wait, this was an Ag accident? Why are we here?" I told he it was because the guy they sent out was a radio guy (it was Sunday). She said "I can't make an official statement at this time, but you should be getting a letter in a couple weeks closing this with no action." R&W says there's no evidence of the accident in my file.
My years of experiences with the FAA do not indicate to me that any level of paranoia is warranted. In all that time I have heard of only a couple of true, factual, instances of inspector abuse, and they were rectified.
In all relationships you get back what you give, if your experiences with the FAA seem to be negative, you might try changing your mindset, because the other other way seems to yield pretty positive results.