I'm the OP. It's been about a week since my tweets. As most of us know, some sites are intentionally filled with promoted garbage (Forbes contributors, a lot of Quora and dZone, etc.).
Many blog maintainers/curators really are trying to be transparent, though, including most or all of the ones I mentioned. They either don't want content that was paid for or will only consider it when they know about it and it's disclosed to readers. For those blog maintainers/curators, here's a few thoughts:
* I think the generalization here are probably that if an author links words/phrases other than a company's name to a company Web site (like linking a type of product or the problem that the company solves), a curator should be more suspicious of the submission. It probably should be changed to link to an editor-chosen neutral discussion of that topic, like a Wikipedia page, trade group, or RFC.
About 2/3rds of the posts that I suspect had a conflict of interest would have stood out this way. For example, one post links "usability testing" to a company. That should stand out during review, regardless of the company or author.
I'd also be suspicious of posts that have more than 1 link to any company. Obviously it could be totally innocuous, but it's unusual and generally unnecessary.
* Don't blindly trust my assessment or the list of companies I provided. As with any random person on the Internet, I can't say authoritatively how any given post was motivated; I can only point to lots of people who are writing very similar things about the same few otherwise-unrelated companies. Each publisher will need to decide for themselves when a coincidence goes from unlikely to impossible.
The lesson here is probably to think about that for yourself: where do you draw the line? Would you prefer to err on the side of false negatives, false positives, or exercising editorial discretion (allowing the article but removing parts about specific companies)?
* I strongly recommend _against_ penalizing authors who are in developing countries.
I think the content marketing firm made victims out of the authors in developing countries. At best, they thought they were providing a real service to the public. At worst, they thought they were making good money doing something that might be a bit shady, but is common in their area. I have no reason to think they knew about the after-the-fact promotion.
(Authors in developed countries like the US - which includes all of the suspected made-up authors - obviously shouldn't be doing this and probably know it. Different rules apply.)
Moreover, someone in a developing country has limited opportunities for career growth and visibility (and some authors clearly have technical talent). I don't think this should justify taking those opportunities away. For example, I do not suggest refusing future articles from these people or otherwise limiting their distribution. Perhaps their future submissions need tighter review or can't be about specific companies/products, just technologies, but it's important that they still have this avenue.
Good luck.