The interesting part was the immediate distrust of the analyzer after propor protocol had not been followed. It's a tool. You have to use it correctly in order to get the desired results. A hammer makes a lousy screwdriver and a screwdriver makes a lousy hammer. Both can and have been used and for various reasons. When you only own a hammer, the world is filled with nails.
Many, many years ago, I ran the student machine and welding shop for the College of Architecture at UF (Go Gators). I would set them up, make sure they were comfortable and then listen. I could always hear when they were abusing it. The best was the band saw, and when it started to howl and the kids stated swearing, I often reminded them "It's not the tool!" Protocol for any gas analyzer is to simply calibrate it against a known gas and ascertain that it remains stable after it's been on a few minutes. The more ideal and consistent the conditions, obviously the better the measurement. If you get a funky reading, before you question the device, go back over the protocol. Did you omit steps or simply didn't bother? Get the protocol down before you question the tool.
Here's another anecdote, when I went to work at a Nissan Dealership, a guy named Henry was doing the the warranty work for them. Henry's a nice enough guy, but he's highly excitable and prone to making the wrong conclusions. Anyway, I was given a number of 'problem' vehicles, not only so they could get a feeling for my mechanical aptitude, but also to get a fresh set of eyes on the problem. One was a Z car who's ride control was not working. It was always a harsh drive, and it was being returned under Florida's Lemon Laws. Henry had spent days on the car. In his words, he had been over it with a fine tooth comb and it HAD to be the RCM (Ride Control Module) or the brain.Yes, Henry thought the Z car needed a brain and he was quick to condemn all electronics because of this. A quick test drive and it was obvious that the smallest bump could cause you to crack a tooth. I put it in the air and inspected the suspension. Lo and behold, the shipping blocks were still on all four struts. Instead of four springs supporting the vehicle and the sway arrested by the struts, the weight of the vehicle was transmitted straight through these hard rubber spacers. They're supposed to come off during vehicle prep at the dealership, but someone messed up. Well, so had Henry. With a flourish for the melodramatic, my boss but a string through the blocks and hung them in our rest area with the sign: 'Henry's Brain!' Henry didn't like me much after that, but the take away here is that humans make far more mistakes than the electronics we rely on. Far more.