Perhaps you can enlighten us on why most all surveyors don't start with decks, or cored hull, present the findings, and then let the purchaser decide to continue or walk away from the rest of the survey. Perhaps if they did it this way, less owners buying boats would be looking for a moisture meter.
I can't even begin to tell you how many of my customers have paid for two or three full surveys when purchasing a boat only to walk away due to deck or hull issues, which could have been caught in an hours time vs. 6-10 for a full survey which was USELESS to continue with beyond the decks or hull.
Yes used INCORRECTLY they can be VERY, VERY misleading and yet piles and piles of surveyors USE THEM INCORRECTLY too. I have far too many examples of this to even count them, all from SAMS and NAMS surveyors. You have many examples of bad surveyors right on your own site. How do you suppose those guys use a moisture meter. Probably not much worse than Joe DIY, I've read those sample surveys and they are a JOKE......
There are many bad eggs out there including bad electricians and bad surveyors. Two weeks ago I set foot on a boat that just underwent an insurance survey. It had a Paloma water heater (non-compliant), an LPG Cozy Cabin Heater, (also non compliant) three LPG tees (stove, Paloma and heater plus a "spliced" LPG hose outside the LPG locker. She also had clear fish-tank hose for the fuel fill, a plastic fuel filter bowl just millimeters from the exhaust manifold and these were only the high points I noticed. The deck was also dripping "coffee", as in rotted core, from the chain plate areas and when you walked on the deck near the chain plates water squished out. This was a SAMS surveyor who conducted this..... The boat passed with flying colors so the insurance company is happy, as is the owner, until he fails to wake up one morning.....
Like you I have dug into piles of decks, I actually work on boats for a living, and compared the results to my moisture meters far too many times to count, so I am not shooting from the hip on this. Are they perfect ABSOLUTELY NOT, and far from it but every tool we have is another data point to help us make decisions..
Bad data is bad data but I still argue that a moisture meter can be a useful tool for a boat owner if they understand some basic principals and also when to call in the real surveyor...
Lets not forget that I DO NOT and have NEVER SUGGESTED that a DIY owning a moisture meter is a substitute for a SAMS or NAMS surveyor.