A bit late to the conversation, but I had an experience on the water last week that, I think, applies here.

I was on a local trout stream that, due to the summer weather and lack of significant rainfall, has become very low, very slow, and very clear. The trout are still there, still feeding, but they carefully examine everything that drifts by.

Well as I was fishing, I noticed midges and micro-caddis were the bugs of the evening, so I tied on a #22 snowshoe caddis and immediately got attention. One good take that I missed on the hookset followed by a few very close refusals. After about 10 minutes, they were on to the pattern and it was doing no good.

So I switched to a #20 griffiths gnat and again got a few eager refusals, but no fish. A few minutes later, not even a refusal. The entire time, there is one brown trout, straight across from me, ignoring everything I've thrown after the first drift.

Out of ideas, and thinking 'what the heck?', I went to the opposite end of the spectrum and tied on a huge (in comparison) #12 olive wulff, usually meant for fast water. I landed it near that brown, who nosed up to it, swam a circle underneath it, and then, without fanfare, came up and slurped it off the surface. Fish on, fish landed!

What made that fish take a fly 3 times the size of the prevailing hatches, I'll never know, but it just goes to show that sometimes a little counter intuition is exactly what you need.