  We study the large N superconformal index of quiver gauge theories describing
the worldvolume of D3 branes probing toric Calabi Yau singularities. The index
has been previously noticed to factorize over the set of the extremal BPS
mesonic operators of the gauge theory. We review this factorization and
reformulate it in terms of zig-zag paths in the dimer model associated to the
quiver. By using this reformulation, we argue that the factorization is valid
not only for the exact R charge but for every set of R_{trial} respecting the
marginality constraints. Moreover, we show the factorization of the index also
in theories with orbifold singularities, previously not investigated. We
conclude by providing an expression for the index in terms of the toric data of
the dual geometry.
