In my personal experience I have found I catch slightly more fish and fish quality increased 20%ish using straight fluorocarbon. Granted a lot of lakes I fish are very clear to gin clear water 15’+ vis.
I will say with 100% certainty I catch more fish on a wacky rig using straight flouro instead of braid.
does braid “spook” the fish idk. Can it make them second guess? I think so.
Stained lakes I’ve experienced no difference between braid vs flouro. 5’vis or less