I never stated that Salmon do not eat them, because I will agree with you that fish are curious creatures, Salmon are a species of fish that are very curious when their mind is set in the feeding mode, which is generally in the ocean, all fish are different, when they enter the river some of these fish may willingly feed on a wide variety of items, some may be very picky on what they will accept, most will have lockjaw, maybe they get a burst of hunger (or curiosity) during a certain hour on a certain day, Salmon are very unpredictable, so saying what they do and don't like can be both right and wrong on any given day.
There is always a lot more to consider than most think when something does or does not work.