Fair.
However . . . if government is not 100% honest, meaning that they hide evidence, then evidence is sometimes hard to find. That doesn't mean that ordinary people with common sense are barred from using that common sense to analyze a given situation. Nor are they disallowed to use past deceptions by government as a reason to suspect current deception by government.
Most conspiracies are explicitly irrational for two reasons, one of which is especially relevant to your point.
1) They don't have evidence to support them. They are stories, backed little to nothing.
2) They're contradicted by evidence. Which the conspiracy theorist ignores.
If the 'government' is hiding evidence, then conspiracies fail on the first point. Without evidence, they literally fill in the gaps with their imagination. And you get crazy ass stories like particle beams in orbit shooting the WTC, North Korean submarines sneaking in fake ballots through Maine, 'Q-Drops', or the entirety of the J6 riot being caused by some dude named 'Ray'.
What you call 'common sense' is people using their imagination in place of evidence. Literally just making shit up. And there's little sense in it.
As demonstrated elegantly by point 2: the conspiracy theorist's irrational denial of evidence, ignoring all the evidence that contradicts them and replacing it with......you guessed it....
.....their imagination.
Worse, once you've got your ticket on the 'replace evidence with your imagination' train, then anything that contradicts you gets folded into your conspiracy. With the conspiracy getting more wildly elaborate, more ludicrously complicated, and more inherently fantastical.
The audit contradicts you?
Well then the republican lead election board must be in on it too! A court rule against you?
Then the judiciary has to be in on it too, they're nothing but corrupt judges! The Republican Secretary of State contradicts you on election fraud?
Well then the GOP must be part of the Deep State and conspiring against you. The Republican AG contradicts you on election fraud.
Why then this must go up to the entire Department of Justice! The whole government! They're all in on it!
There's no sense in any of that. Common or otherwise.