Agree! The gas never washes the intake valves. All the fuel injector cleaner can do is clean the fuel injectors! There are treatments that can be injected into the airstream through a vacuum port that claim to clean the valves.
I’ve been meaning to run an endoscope into the Audi DI engine we have just to see. Plus it allows me to use my newest tool, a lighted endoscope that sends the image wirelessly to my tablet in full color. Only $40!