Well at very least these USAF/USN Stealth jet programs are at least competent at secrecy. From an Occam's Razor perspective, it's almost certainly that UFOs are either strange optical aberrations in peoples camera lenses or experimental military aircraft, so in part I think I agree with your dad. Camera weirdness being more common than billion dollar black programs, and those being more common than apparent life in the universe.
My father worked in connection to some of these programs many years ago (long since retired), and his favorite quip was to suggest that a closer inspection of "real" UFOs would reveal a USAF roundel painted on the side. So, naturally, I'm inclined to believe that if any such thing were ever spotted, it would be the result of one of these programs.
