Personally I believe that it depends on the clarity of the water in regards to sight feeding, on rivers. Trout rise to fly and take nymphs etc, when its presented to them in clear water, but will struggle to see fly on the surface, when the river is in spate. ( again this depends on the river ). If you put a spinner past their nose, they will take.
If your fishing a carp lake, that has a healthy head of fish, the water can colour very easily. The fish probably rely on smell to attract them to the bait, but then closer in can visibly make distinction between different baits by sight. ( again d