"...and I don't take any advertiser money..."

What counts as "money"?

I think the answer is "a lot of reviewers don’t take advertiser money." This is not a field to get rich in.

I think that reviewers have a spotty record for trustworthiness for a different reason -- they like to start trends and follow trends. That gets them attention. It’s an attention economy, not a bribe-taking scam.

But most audiophiles know that good sound does not come from trends but from patient, methodical, and often non-consumerist solutions to acoustic puzzles. The best speaker makers may not be the best advertised, expensive fuses may not be the way to correct a bad system, and used gear may be the fastest way to the mountaintop. None of that makes for trendy content.

One way around the trendy approach is the be the "maverick" dude who "tells it like it is." We all know that guy with his "truth to power schtick." Sometimes he IS telling the truth but the point is always hammered in, relentlessly: "Only I tell you the truth. Others are out to scam you. I’m on your side." (Sounds like a politician.) But then, guess what? He has his own gear to sell you, so now that you’ve realized he’s the only one you can trust, you have a supplier to whom you can pledge fealty. Now that’s some grade-A flimflammery.

There are a bunch of other reviewers who seem, to me, to really be doing honest work. Steve Stone, Hans Beekhuyzen, Tarun, and a few others. 

Why is it such a difficult thing to  believe?

If anything, a reviewer might get an " industry accommodation"

to purchase the gear after evaluation?

@carlsbad2 The whole audio hobby consists of two parts, IME. One is made up of folks who are there simply to try and make a buck ( most if not all reviewers and others). For example, on one of the many forums I am banned from, one of the owners without totally realizing his mistake, disclosed that they do take advertising as a means of being profitable. When pushed, the forum ’geniuses’ revoked the membership of a manufacturer who had started several posts simply to expose his gear more fully, and who saw an opportunity to do so at no cost to himself.

Then we have the other type of hobbyist, that is the one who usually comes here, and is more interested in bettering his system and his musical experience. Personally, I am only interested in the latter.

Couple good discussions of this topic:

https://youtu.be/6dwT5uWRMXQ?si=NEEpaOKfwnWQ8ree&t=117

https://www.youtube.com/watch?v=yhn1ELAqhw4

Key point: a reviewer who wants to keep his audience has to get the sound right. If they're being paid, they lose too much of their audience for it to be worth it.

These claims about audio reviewing, not about advertorials. Those are a different animal.