  The production and decay of exotic leptons are discussed in the context of
the vector singlet, vector doublet and fer\-mion mirror-fer\-mion models, at
c.m. energies $\sqrt{s}=190GeV$ (LEP II) and $\sqrt{s}=500GeV$ (NLC). The model
dependence of total cross sections and kinematic distributions at these
energies is shown to be weak for these three extended models, indicating that
it would be difficult to establish which of them is best fit to describe the
underlying new physics, should exotic leptons be detected. We suggest that, in
order to resolve this difficulty, one should measure the angular distributions
of single exotic leptons in longitudinally polarized $e^+e^-$ collisions.
