I have a 798 and an 898 and you can run over a spot and the 2 units will show different things.they just interpret. and display things in a different way. yes, fish what you see until you learn what you unit is telling you, and yes you sometimes you catch fish where you don't see any, especially where fish can hold tight to cover and look like part of it.it's a great tool though, and it will help you catch more fish. just keep spending time on the water.