Awareness of the dream requires a certain room for that awareness, a freedom from being occupied with all kinds of emotional or intellectual issues. Not being attached. I think that the post yesterday about inner peace gives a number of signs that might predict whether a person could have lucid dreams.
The freedom of attachments may also show up in the content of the dream, in many ways: perhaps less aggression and more a generally upbeat mood, more reflective thinking, a higher consistency of the story of the dream, perhaps more fantastic elements, or a use of different (sensory) channels of information, perhaps even the disappearance of visual elements all together, just to name a few things. I'm sure that with a little brainstorming, you could create a long list of items that might occur more frequently with dreams of frequent lucid dreamers.
Photo by Montana Raven