No, I enjoy reading the opinions of others that are based on something. However, I did not feel like reading an essay of undetermined origins. If someone wants to say they think that something like a certain footprint is a 'trigger', or something else is, that's fine. But if someone wants to say that something is a trigger because so and so says it is, that's B.S. I've read many books where the author says that his/her fly pattern is great because such and such is a trigger. Yet, sometimes when I ask fly fishers if they've used so and so's flies, the answer is 'Nope. They ain't worth squat'. Or something to that effect. I've seen a name bandied about these threads and posts as an authoritative expert. Well, back when, and for 3 years straight, I saw that person hawk 3 different brands of fly hooks. Each year he/she raved about the brand of hook he/she was hawking. Of course maybe there was $$$ tied to the supporting advertisement.
At any rate, and talking about dry flies right now, I believe there's something about every fly that causes a trout to take it or not. In fact, one trout may let a fly go and the next trout along the current may ingest it. What didn't trigger one but triggered the other? We'll never know because trout don't talk.