There's nothing inherently unethical about it, and I say this because you're acting like these people are brainwashed or evil. It's a counter-espionage and intelligence organization that deals with both overseas and domestic affairs.
Unethical means unethical, not evil (though the latter is generally the former), and it's incredibly easy to commit unethical acts without being brainwashed
or evil -- alway's line of justification is a really bloody obvious example of how it happens, as is the fact that pretty grievous violations of what once was at least a facsimile of a right to privacy is something you're willing to write off as "counter-espionage and intelligence that deals with overseas and domestic affairs". The country in general, and definitely the organizations in question, consider their unethical acts to have a sufficient practical payoff to justify those acts on a pragmatic basis, but that does not somehow magically make those acts ethical action.
And as SG puts it, yes. Not all action performed by these groups are unethical, but we've been finding that quite a bit
is. And if a person's willing to perform those unethical actions because the pay (directly monetary or otherwise) is good, well. That says most of what needs to be said on that subject.
The NSA hasn't done anything that wasn't implied or what I deem morally dubious.
... as you might imagine, there's a fair number of people that would disagree with you at this point.