It is very naive to think that governments should have no secrets. Here is an example: You negotiate the exchange of one of several American soldiers who are prisoner in a foreign country, and of course you want them back. The foreign country says: "OK, we will give this one back to you on the condition that you never say in public that we tortured him." It is horrible and unpleasant, but what are you going to do? Publish this in the media? What about not only this prisoner, but the other ones?
It is not an unrealistic example. One time, when Franco was still dictator of Spain, the Spanish government promised not to execute a political prisoner on the condition that his lawyers did not publicize the fact that he had been tortured. The lawyers were indignant because it is a disgusting deal and they went to the Press. The prisoner was garroted. What good did that do? It is easy to defend your principles with the life of somebody else.
The best example we know of secret deals happened during the Cuban crisis in 1962. We escaped narrowly a third world war thanks to a deal between the USA and the USSR about the withdrawal of US missiles from Italy and Turkey. If you think that you could have done better, go into politics or work for the State Department: don't blow what your Government does by publishing it to have your name on Facebook.
If you dislike what your Government does, vote for the other guy next time. Half of the country does not like what the Government does, then it is the turn of the other half to be unhappy about it. We call this democracy, we have no need for traitors.
What the USA did wrong during the Cold War was very public and accepted by everybody at the time, such as favoring fascists over democrats as foreign allies. Maybe we should protest the crimes we know before we protest the conspiracy we don't.