I chose the "Yes" option. And the reason for it, is because it is a question with open ended answers that may or may not be answered in our lifetimes. I have personally never seen or experienced anything out of the ordinary. But I will go by probability and estimation alone in answering this question. Here is my take on it:
The universe is a huge place. I believe astrophysicists have stated that there are more stars in the observable universe than there are grains of sand on all of earth's beaches and deserts. Each one of these stars belong to a system of planets, planetoids, comets and other stuff with peculiar laws of motion and thermodynamics much like our own. Of course, a vast majority of these worlds may be dead and void of any biochemistry, just like Mars or the moons of the gas giants. But there may also be worlds just like Terra, which lay just in the habitable zones of their stars, thus enabling biochemistry, DNA, and eventually life to arise and flourish.
Earth and it's solar system is relatively young compared to the age of the universe so far. If worlds just like Earth had formed in the early stages of the universe's formation, there could be a possibility that entire civilizations have rose, achieved great heights, and fallen in a vast period much like how empires have risen and fallen in earth's history. Arthur C. Clarke have mentioned this a few times in the epilogues of his Odyssey series when he talked about the elder race that left the monoliths all over the solar system.
All of this leads to this one conclusion: Civilizations which have mastered the extreme difficulties of traveling amongst the stars would possess technology so advanced that we would only perceive them as magic if we see it. Thus, if they wanted to "visit" us, they do not have to come here in spacecraft or flying saucers giving off detectable light and heat signatures. They can simply observe us from afar, with instruments that would make our Hubble telescope seem like a pair of opera glasses.
Ever since we had invented radio and wireless communications, we had been busily pumping gigawatts of energy into space. And the lights from our cities would clearly be visible on earth's night side. So, if anyone "out there" is interested in observing us, they will be doing so. And we will not know a damn thing about it, unless they choose to make contact.
I am a person of rationality first and foremost. If something is not observable or detectable by scientific means, I tend to dismiss it entirely until it has been proven scientifically to exist. Supermarket tabloids and doctor's office gossip magazines do not qualify as scientific. But when it comes to technology and the possibility of technology's progression from here, there are much "what if's" to consider.
