Evidence is mounting that agencies within the US gov't are up to no good. Given that the main one is the NSA, an agency with a fair amount of expertise at keeping secrets; it shouldn't be a surprise that great smoking guns of evidence aren't bursting from within the place.

Not any, definitely not all, but the government's lack of transparency and recent actions means that we doubt it to the core. Also, "we know it actually did" is a terrifying thought when the government decides to hide whatever it wants whenever it wants. How will we ever know?

No, because the majority of people in power (and a few of their minions) have immunity, both legal and practical. Innocent until proven guilty does not apply to them if they can't be prosecuted to begin with.

Yes I know this isn't a legal argument, but if someone receives immunity for actions that would otherwise be unacceptable they should not receive the benefit of the doubt when accused. The burden should be on them to prove they deserve our continued trust.