I think this is the downside of intelligence. You see so many patterns you start to believe that everything falls into one. New ideas are assumed to be no better than old ones.

I don't think it should matter where an idea comes from. I read an article from Fred Wilson that mentioned (in a good way) how surprised a CEO was to find so many good ideas coming from customer service reps (who have the most direct experience with customers). I won't assume you ignored interns, but I think stereotyping by position is a good recipe for overlooking opportunities, just to save yourself some mental fatigue.