I actually wouldn't say all of them are reptilians and greys.. Of course, I would say that many of the UFO sightings may not be actually alien spacecrafts at all. At the same time, you also must realise that there are several alien races in the universe. Some of them may have been visiting earth from times we don't know. There are also accounts that say that while all our gods left the earth, some of them chose to stay back to help us grow. There are also accounts saying that some of them have continued living here followed by their generations for thousands of years. If that is true by any chance, then it may be possible that they are still on earth.
I was just reading about a place called Gyangunj in the disputed border of China and India.. Sounds like an interesting place. Some say, it is an abode of alien species who gave us the right knowledge from time to time and some of them say that these are our ancient sages or 'rishis' who gave us the knowledge. Apparently, it is not visible to naked eyes, but only people with sufficient spiritual ascension can see the place. The place cannot be detected by today's technology either.
So, anything is possible. But, better to be skeptic and weary about any UFO sighting you hear or see, because you never know what is friendly and what is not, or what is true and what is false. Trust in yourself and trust in our gods of hell. They will be there for us.
Hail Satan!! Hail Enki!!