I agree the way of categorizing I had started with is very flawed. It may not even be necessary for me to quantify a "level" of the persons experience. There are a couple of people who teach lucid dreaming, and I wanted someway of qualifying their experience, to distinguish why I ask them some more general questions about trends observed in lucid dreamers in general. Its probably fine to just ask do you teach lucid dreaming, and if so then thats a particular marker.
None the less the qualities listed by the responses in this thread will be useful to consider. It could provide some interesting data to play with in a qualitative way. Working backwards from whats interviewees describe, rather than trying to create preformed criteria.
Thanks alot for thoughts and feedback. May ye be rewarded by stunning lucid dreams occurring by surprise :-)