  We investigate the origin of the regular features observed in numerical
studies of the interacting boson model with random interactions, in particular
the dominance of L=0 ground states and the occurrence of vibrational and
rotational band structures. It is shown that all of these properties can be
interpreted and explained in terms of a Hartree-Bose mean-field analysis, in
which different regions of the parameter space are associated with geometric
shapes. The same conclusions hold for the vibron model.
