Yes, I believe that some flying objects could potentially be unidentified.

nanno nanno

with my own eyes

It is entirely possible that a lack of UFOs (being defined as alien spacecraft, not just something in our atmosphere that cannot be identified) does not necessarily mean that there is no other life outside of our planet. They may be on the same time line as us and haven't been able to explore outside of their own solar system yet.

Chariots of the Gods is a very interesting book that tries to explain many things on Earth were actually created by spacement who visited here. It was the inspiration for several popular sci-fi tv series and movies.

If you talk about visitors from outer space, I would say 'no', since distances are simply too far. It would take thousands of years of travel in even the best case.

If you talk about loonies, dopers and drunkards seeing something strange, then I would say 'of course!'

there are things in the sky that are at some stage unidentified, these are UFOs.
Once they are identified (as they invariably are) they're UFOs no longer.
So yes, there are UFOs but no, they're not extraterrestrial spaceships.
And yes, there's likely life on other planets but no, they're not going to come here to snoop around.

There is actually nothing very interesting in CotG; every significant factoid mentioned in the book that was not an outright lie has been debunked - thanks for pointing to the wiki, rather than, say - pointing to one of these sites.

(digression) Here in Seattle there was an ice cream parlor in the 'U District' called DanKens - we used to call it Van DanKens - Ice Cream of the Gods. It was really, really good ice cream(/digression).

I used to visit some of these crackpot sites but they eventually began to run together - way too many bangs (!), weird underlining, and random capitalizations. I say "if any paragraph has more than one bang, they're a crank!!!"

(new digression) the British call bangs 'shrieks' - which I kind of like ie MATLAB GEEK: look right here you want a shriek so you 'shell escape' "(/new digression).

Coincidentally, there was a recent "UFO sighting" in Texas. Stevensville, I believe is the city name. It has recently received national attention.. apparently many people saw some 'unidentified' object.. The initial two responses from the government were that they had no idea what the object could have been. However, the government recently made a new statement saying that there were actually F-16s in the area. This, of course, has created no government conspiracy theories..

As to the idea of other life out in the universe.. I think the obvious answer is: Yes. Seriously, now.. the universe is infinitely expanding.. The probability that there is other life somewhere out there is approaching one indefinitely. The real question is whether we will ever make contact with other civilizations. Unfortunately, the universe is huge.. and most likely not navigable over great distances.