I think the author makes a good point by actually testing what he's seeing and the changes he makes to his unit by placing items in the water, like balloons.

He adjusts his unit, makes some passes, and then adjusts again until he's clearly able to understand what he's seeing.

I liked the video that was posted of the Texas crappie fisherman where he was showing what was fish, clutter, and species of fish. helped me a bunch..