A friend of mine is an orchard manager and uses the attractants each year.  His motivation is to get the bees in the trees rather than on the dandelions.  His empirical analysis is that the attractants work (for him).
 
He mentioned these attractants when I asked if he mows prior to bloom to keep the bees off of the more desirable (to the bees) dandelions.  He claimed that it is less effort to spray the attractant than to keep eliminating the dandelions.