  I demonstrate that if an anisotropy in the arrival direction of high-energy
cosmic-ray electrons and positrons is observed then, barring local anisotropic
diffusion, dark matter annihilation is ruled out as an explanation to the
positron excess. For an observable anisotropy to originate from dark matter
annihilation, the high-energy electrons and positrons must be produced in a
nearby clump. I consider the annihilation pathway producing the smallest flux
of gamma rays versus electrons and positrons, and the combination of clump
distance and luminosity that minimizes the gamma-ray flux. I show that if an
anisotropy from such a clump were detected, and if such anisotropy did not
generate from anisotropic diffusion effects, then the clump would be clearly
detectable as an anomalous, bright gamma-ray source with the Fermi Large Area
Telescope. I also point out that the non-detection of an anisotropy is
perfectly compatible with an astrophysical origin for the excess positrons that
has nothing to do with dark matter.
