The only way your position that government conspiracies are generally loony and false can work is to believe that the government is inherently good and working in favor of our interests rather than its own.
So again, why should we believe that?
You really love putting words in to peoples mouths. Not all conspiracies are false and not all governments are the same. So sure, some governments (and dictatorships in general) are bad and some do conspire, but that doesn't mean it's always the case and it doesn't mean every conspiracy is true if one is. You really need to stop being so presumptuous.
Oh, so "some" governments are bad and lie. Can you tell us which ones are good and selfless which ones are bad and selfish?
From what I can ascertain in my short time on this site, Tom, you and I likely share a lot of philosophy about government in general.
As an American (and also one who thoroughly enjoys reading history), I am pretty skeptical of all governments in general - they will invariably seek greater and greater control and authority over time (perfect example: the US presidency which is supposed to be one co-equal branch of three, but in many respects has become "more equal" than the other two).
But the way I would put it, is not that people in government are bad and lie, but rather they are self-interested in their roles, like all people, which leads to mission creep in their organizations, and small power grabs individually that over time lead to something unrecognizable from the standpoint of 1776.
In short, it's due to the issues brought to light by Public Choice Theory:
https://en.wikipedia.org/wiki/Public_choiceNow, with that preamble out of the way, there IS a simple way we can tell which governments are "good" and which ones are "bad" in my view:
How much individual liberty (including economic liberty) is available to each individual? Some nations offer very little, some nations offer a lot more. None offer absolute freedom (although in my view, that's also because pure freedom fails at the outset, since someone free to murder you means you are not free, and so pure freedom is a logical contradiction). But in practical terms, there are governments that offer immense amounts of freedom relative to virtually any other century in history, and relative to many others currently in power.
Examples of relatively freer countries on the far side of the spectrum include the US, Canada (and the former UK commonwealth nations in general), Taiwan, Japan, S. Korea, and most of what is termed "Western Europe."
Examples of relatively much less free countries on the other side of the spectrum include China, N. Korea, Iran, Uzbekistan, Myanmar, Libya, Sudan, Algeria, Egypt.
There's a wide variety of country types making it difficult for even those who study these things to classify them. But you can look into how effective governments are at establishing and maintaining the institutions that lead to more freedom (e.g., rule of law, independent judiciary, smaller government, freedom of speech, assembly, and religion, etc.).