I listened to the podcast a while ago.
His conclusion that color is the reason for a refusal, at least at short distances where they can see color well, may be true at times, but in my experience this is a rare occurrence. Drag is much more likely to be the reason for the refusal in most cases.
Most of us, myself included, overestimate the distance a fly can drift drag-free and the fly begins to drag a small amount without us being able to see it at 20 or 30 or 40 feet away. But the trout can see it, and the fish rejects our fly and turns down to heads back to its feeding station.
After this happens, many many times, I've used the same fly (in the same color of course) just after a clear rejection from a trout and caught many fish afterward when I was better able to get a good drag-free drift over other risers.
So I would automatically assume, when you see a closeup rejection from a riser, it's because your fly is the wrong color, and a simple color change is the key to vacuuming up a stream of rising trout. That is seldom the case, at least in my experience.
In order of importance for success:
1. Presentation (the perfect fly with poor presentation will likely not work at all)
2. Size
3. Shape
4. Movement (soft buggy materials)
5. Color (matching the exact color of flies seldom as much as the above things)
