Excellent thread and great post TS.
kgoerz, thinking about me again?
I would say there is only one sure way to know, and that is trigger time with the individual in question. Although the research and tips will definitely help narrow the search.
The instructor-stud relationship is a funny thing. One man's "God's Gift" is another's ass hat.
Word of warning - a badge or diploma, even if real, does not necessarily guarantee expertise.