You are right on the money. Substitute "demon" for "alien" in any of the UFO literature and certain correlations come to light.
Both are reptilian in appearance, can inhabit the bodies of corrupt humans, and have startling powers. However, they are doomed to operate behind the scenes because they are not really natives here and must use us as proxies to further their aims.
Not all are reported to be reptilian in appearance, only some. Not all are described as "creatures", they are also described as "beings." It is just too easy to say they are demons.