If aliens exist we will likely never know.

I think if aliens do exist we will probably never know because if they were advanced enough to come here more than likely they wouldnt hide or form pacts with our govts. I think that there could be civilizations similar to ours all over the universe wondering the same thing.

i'd go even further than you sometimes i wonder if a civilisation advanced enough to travel across te galaxy would even care about our small blue planet infested by a bipedal parasitic lifeform doing it's best to destroy it's own habitat and other lifeforms.
What would we do if faced to a similar situation , frown in disgust, ignore and just continue on our journey or even cleanse the planet, after all Star Treks first directive sounds good but it's still only television.
Remember one of the old twilight zone episodes, a race of super beings land on earth cure cancer, end wars, invites the human population to move to their planet onboard huge spacecraft (but not without weighing them prior to the trip) until someone finaly manages to translate one of their books called "to serve man" and finds out it's a cook book
another problem i see is cultural differences , we can't even get along or understand each other on a single planet or even on a continent or country.
Doesn't really give a positive perspective on all of this

your theory is plausible, but they probably wouldn't waste time on us if they're so damn advanced. they also might not be that advanced, and then the only form of communication would be interstellar phone tag.