Very good post! I think it also has to do with as you said, heavy fished. Like the stillwaters, some have heavy pressure like skiers, boaters, etc and the fish are use to that. Same with some rivers.
Gin clear, is one I think you want to blend in all the way. But deep fast running pools I would think, are not evident.
I however seldom see the glint or flash off reels, although I am sure it happens. Leaders, well I can see that also, thank gawd for thread leaders LOL.