My experience has been mixed. If the time is right and the right deer sees a buck decoy, the action can be fantastic. Of course, you can also have negative reactions or no reaction. All in all, I have not found them to be worth the work in my area.
However, I have had good luck in one situation. It is using a half body fetherflex bedded doe for archery hunting. I don't use it for attraction, but for positioning. Deer are always moving in nature, flicking the tail, rotating ears, and more, unless they detect possible danger. Then, they will often freeze trying to identify it. My half-body bedded doe has alert ears with head up, staring in one direction.
How does a deer react when it comes through the woods and sees another deer in this position? They keep their distance, circling cautiously behind the alert deer, looking in the same direction trying to identify the potential danger. So, I position the bedded doe where it can be seen in open hardwoods about 40 yards from my treestand looking directly away from me. I don't want it looking directly up-wind but more at an angle. Other deer will be about 20 yards from my stand looking away from me presenting an opportunity to draw and shoot.
I don't do this if I'm trying to shoot a mature buck, but it works great for positioning does and young deer for an archery shot.
Thanks,
Jack