I think therein lies a key point, not just proximity to salt, but also lack of pressure and/or exposure to predatory influence, man or other.

I have had wonderful days catching silvers on the fly. Mostly in cases similar to what you describe. My local streams are 3-4 days from the salt for most fish, and many show up having felt, or feel pressure shortly after arrival. As in WA, lots of the biters seem to get weeded out early on, and the more tight lipped fish mill around in the meat holes for a while staring at spinners and spoons all day as new fish roll in and perpetuate the cycle.

Showing them something they haven't seen, or in a way they haven't seen it definitely seems to work. That having been said, I have had more days than I can count pulling out every trick on the book trying to get stingy WA silvers to bite. Sometimes they just don't.

Knudson's Spider is a new one for me though I will have to give that a try shortly after hell freezes over and I fish for silvers in WA again!