On some of my guns the flush tube (from Track, probably the same model) worked okay, on a couple, it wouldn't work at all. Key to working was being able to get a good seal of the o-ring over the touchhole. I could get water up the plastic tube and maybe up a foot in and out of the barrel; i.e. it was useful in cleaning the breech area, so I wouldn't call it junk.
That said, I've since gone away from using it and instead find it easier to plug the touchhole with a toothpick, soak the fouling with cool water, and just fill the barrel via the muzzle and pour dirty water out on the ground. Could be there are some breech types and shapes where the flush tube would shine. For myself, I found the flush tube prone to leaks around the o-ring (and hence down the stock and into the lock mortise) and prone to having the plastic tube slip out of the bottle or can holding the water and making a mess on my garage floor.