Catchy phrase, dont you think?
IMO, either no movement or improper concealment is the culprit for flaring ducks.
If you have a spread of the finest decoys made and no movement, as in flat water & no wind, then it just doesnt look natural. Flocks of ducks are always moving, swimming, stretching, dabbling, diving, etc.. Had a day on the bay where the wind was intermittent, 5-10 mph one minute, flat the next. if the ducks came by when the wind was blwing enough to put a ripple on the water, they dove right it. If they happened by when the wind & water were flat, they would come in to about 75 yards & then rise up & head in another direction.
On the other hand, if your blind does not fit the surroundings, or you are moving too much or have something that just doesnt look right, as defined/seen by the ducks and who know what they are thinking/see most of the time, then the ducks are going to flare. Why? Who know? What worked one day, doesnt the next. Same conditioned, same setup, et.. but birds are flaring. Why??????? I've heard guys say shotgun shells floating flares birds, decoys lines to bright flares birds; decoys touching flares birds; decoys to close together/to far apart flares ducks, etc.....
None of us will figure it out 100% of the time. If we spend all our time trying to out-think a creature with a brain the size of a pea, we will go mad. If we arent mad already.