I have been in the wet submersible business since the late 70s and I have used several different obstacle avoidance sonars.
For the past 4 years I used the Interphase Sea Scout then recently we switched to the Interphase Color Twin Scope
I find the Color Twin to be about the best forward scanning sonar product I have seen in years.
Sonars are all prone to interference
and clutter and most often operator error.
The real key to getting the most out of any sonar is proficiency through practice. You have be able to interpret what you see on the screen
. That likely wont happen if you only look at the screen
in confined or hazardous areas on occasion.
The way we teach new users is by driving past and towards known obstacles and through narrow channels.
While doing that we have them manipulate the controls to see what the effects will be.
The point being, It is often quite simple to tune out or obscure the obstacles you are looking for.