I imagine we all have some particular fly pattern that we have never caught a single trout on. For me it is the Humpy. I have tried it of dozens of times and never even gotten a strike. It has not been for a lack of trying. Dif colors or dif times of day or dif hatches or times of year have not helped. For me it is a real dud! I gave them all away this year and had to go thru 4 guys B4 I found a guy who would take them as the others had little regard for them. One guy said if I gave them to him he would only take a razor blade to them to save the hooks. What's your nemesis?