You really, really don't want a government who can build a unified profile on you in that way.
There's a question of what you mean. Is it, can they be corrupt? have they been corrupt? are they currently corrupt (because of the previous, or incidentally)?
Plato thought Democracy was corrupt and it's the least inherently corrupt system I know of. I would say they are fundamentally corrupt. The best you can do is try to limit it with a document (like the US Constitution) and setting up a multi-branch power structure capable of adversarial action. As you point out, the US does not have that and it's showing.