I attended a fishing class long ago where a decoy straetgy was discussed. The idea presented was to have one guy cast a weird type of buzz bait deep into cover and burn it back to the boat, while the other angler casted right behind them with a standard bait, bucktail or whatever you prefer.
I can't describe the buzz bait he showed us other than it looked like a paddle wheel to a steam boat surrounded by a plastic frame (no hooks). The idea was to get the muskies attention with the decoy and get it to hit the lure behind that. I remember my buddy & I saying at the same time, you get to cast the decoy & I will cast the bait.
Never tried it or have seen it used, or discussed in any of the many seminars attended.
lots of people consider a casted lure to be a "decoy" when sucker fishing.
ie., get the fish to follow the lure to the boat where they see and eat the sucker.
If your questioning the decoy pictures that Zielke Experience posted, there for sturgeon spearing on lake winnebago. Which i dont know why you would put something like that on this site? Interesting guy...