Hey Fank- I do believe that at times fish can and do turn down flies because the color is off even on real small flies. A parachute Adams is not a hatch matching fly it is what I would call a searching pattern. It dosen't imatate anyone thing but may look like several things. And yes I have seen fish flat turn them down.

I should say here that when I tie Parachute Adams in small sizes I just use the Grizzly hackle and do not even put the brown hackle on the fly. I find the fish don't seem to care much. They do work well on a Baetis hatch at times. I also believe that the grizzly hackle makes the fly look like it is moving and that draws takes. Ron