There you go with that grain of salt business. You repeated yourself so I'll repeat myself:
Let me tell you a little story that would clarify my point about trusting experts and witnesses to truth. Before I moved to NJ 8 years ago, I was living in NYC, the boro of Queens. I was called for Federal jury duty at the Eastern District in Brooklyn. It turned out it was a Mafia case where a few guys were charged with murder, conspiracy to commit murder, and a few other acts of miscellaneous mischief, mostly against other gangsters. There were over two hundred prospective jurors. Everyone was given a number. Names were kept secret and not used. We all had to fill out a 30-40 page questionnaire relating to the case and our personal beliefs. One of the questions was "Could you believe a convict as a juror testifying for the government" I didn't like the answers you could check like yes, no, and don't know. I wrote on the side -
It depends.Unlike most juror screening at civil trial where everyone pretty much all sits around, each prospective juror was called separately to the very courthouse where the actual trial would be held. I had to sit in the witness box and swear to tell the truth. The defendants were sitting in the court along with their half dozen lawyers,. Also present was four government prosecutors, all considerably younger than me. There were about half dozen armed marshalls. It was very intense. The judge asked all the questions that were given to him previously by each side. He finally got around to asking me what I meant by It Depends?
I told him if I was in jail, and was promised to get out early if I testified, put in a witness protection program, and sent to New Mexico to sit by a pool for the rest of my life, free, drinking Pina Coladas, I might lie to help the prosecution, or at least embellish the truth. So as a juror I couldn't believe a witness like that. However, if the prosecutors, and I pointed to the four of them and looked them in their eyes, could come up with a number of witnesses who were in different jails who could independently corroborate each other's testimony, then it might be more believable.
I wasn't chosen as one of the jurors. The actual trial went on for about 6 weeks. The jury found them all guilty.
I hope that clarifies how I look at things.