I fish plastic a lot without problems and love them. Over all they are the most effective fishing method we have available to us and work well on all Pacific salmon species and at all depths -very versatile but they have no action of their own. You either have a swivel problem (most likely and often on the flasher) or a combination swivel and leader problem. Hootchies need a very heavy leader to transfer energy and motion to it from the flasher. 48 lb to 60 lb test is not too much and I usually use 50lb test. Salmon in the ocean are not leader shy. I also want that leader to be of the hard abrasion resistant type of monofilament. If it is soft and supple that is a good mono for a casting but not good for resisting twisting and transferring energy/motion to the hootchie. As a bonus, it also resists teeth abrasion related break offs. My plastic rigs have added weight to them by the way they are rigged with an insert, large head bead and a small internal swivel attached to a large single stainless hook. If hootchies are riged heavier, to keep them having a good lively action you either shorten the leader a little, or go a little faster, or a combination of the two. When I have had a flasher swivel go bad, it is usually on the line end of the flasher, not the leader end and yes it can come up with twisted up main line.
PS With your side by side testing between the spoon and the hootchie, have you tried exchanging the flashers between the two and see what happens. For that matter change the rod as well, as it could be the main line terminal swivel.