What do we really see

Can you trust your eyes? Is what you see real? Can a witness be counted on to tell the truth when it is so easy to discredit the testimony?
Many questions and not near enough answers. I was watching the history of aliens this weekend and after 2 hours of testimonies everything had an alternative explanation. And I mean everything! It made me wonder if we can trust what we see, we don't have "super vision", and our brains can perceive things that are not there. Hypnosis is not reliable as again the brain is very good at making things up. So that question came to me, "what do we really see"?
How about dark matter, this substance has been proven to exist but we cannot see it. Magicians use slight of hand and miss direction to deceive you from seeing the truth in their tricks. I could go on and on but the answer keeps alluding me, can I believe what I see? Is this how religions started? With misdirection and deep mental hypnosis did the founders of our religions just pull the wool over our eyes? And what of all the unexplained UFO sightings, are there that many people that were fooled into believing or not believing what they saw?
Like the Oracle said in the Matrix, this really cooks your noodle as to what is real, and what our brain makes up. 7 billion eye witness's and no one saw a thing!