Another way to approach the broadest version of that topic is to consider that the nature and purpose of intelligence agencies means that they want links with almost everyone. But that the nature and extent of the links vary greatly, and do not in themselves provide a concrete guide as to the reliability of a particular source. Same goes for other state entities, state funding of causes that there is political or economic motivation to fund, etc. We can even chuck in some generalisations about the sort of entities that can be made use of more directly by specific intelligence entities. eg we know that businesses, ngos and journalistic roles can be used as cover because they come with plausible reasons for particular travel and interest in subjects and conflicts, and foster networks and information gathering. And there is always an obvious use for dissidents by external players. Then we can add a layer involving the sort of games where states are often aware of specific individuals who are suspected of holding such roles, and of suspicious funding links, but outside of dramatic escalation of tensions tend to prefer to observe rather than expose relevant individuals and organisations. But then we also have to consider that publicly accusing entities of such links is a classic propaganda technique, and that versions of this exist where the accusations have some truth to them, but also versions where the accusations are a disgusting smear with zero basis in fact.
Balancing acts around such themes arent trivial to perform, and those who become hypervigilant about such matters are at just as much risk of shitting the bed as those who are hopelessly naive. When you come to see the hidden hand everywhere, that murky world has managed to gain influence over you via a different path, has found a different way to stain your spirit, isolate you, narrow your worldview and fuck with your credibility. Effort must be placed into finding counterweights to balance against this so that you dont end up in paranoid limbo. Or ending up trusting the wrong sources just because they appear to align with your resulting worldview.
I do not have a simple guide for pulling off such a balancing act. But I suspect it at least involves setting a rather broad range of acceptable source credibilities. Dismiss out of hand only the very most extreme of sources, and find other ways to evaluate the substance that every other source offers, even those for which it is reasonable to attach some degree of suspicion. Do not ignore your suspicions, but do not allow them to block out the light or close down possibilities prematurely, or to limit you to what becomes a too narrow and well worn path with too much rigidity of thought.
