A person well versed in methods, should at least know a thing or two about the things they're advising. If it sounds like they're reading it from a webpage or a label, they're probably reading it from a webpage or label.
This is a general rule I apply to gardening: it's alright to be wrong about something, it's alright to not know everything and still share that piece of info, but stating unproven things you've read online without trying them yourself as factual is a bad practice. And this happens more than you'd think.
Diatomaceous earth as a bug killer for instance.. As if ground dwelling animals that have been here since the dawn of time are suddenly going belly up by the stuff they've been exposed to for millions of years. They made an exoskeleton, trachea, tiny hairs and whatnot to keep the stuff out. "It works!" I hear the people cry. Until they water, and then it doesn't. "But the label says..". Exactly. The. Point. Of. A. Label.
There are mountains in the world, beaches all over, buildings, all shedding sharp rocks by the million tonnes a day. If bugs would be hurt by it, you'd think they wouldn't have made it this far.
I thought I knew a lot about plants, but bonsai taught me I was wrong about that. I've seen more weird things happen in bonsai than I have in regular gardening. Usually positive things.
I can confidently tell if plants are going to survive in their current conditions, or not. Honed some serious skills that I already had, but took them to a level I didn't know existed.
I learned how to appreciate ugly trees. Or maybe the people keeping those trees. If you can refine an ugly piece of tree that's never going to win a show, and make it so that everything looks perfect, you have earned my respect. To make something crappy look less crappy and paying attention to the details even though I believe it's not worth the effort, to me is a sign of character and resilience. It doesn't matter anymore, it's not about the tree, it's about the person doing the work and doing it well.