  [Abridged] We present ISO far-infrared (IR) observations of 21 hard X-ray
selected AGN from the HEAO-1 A2 sample. We compare the far-IR to X-ray spectral
energy distributions (SEDs) of this sample with various radio and optically
selected AGN samples. The hard-X-ray selected sample shows a wider range of
optical/UV shapes extending to redder near-IR colors. The bluer objects are
Seyfert 1s, while the redder AGN are mostly intermediate or type 2 Seyferts.
This is consistent with a modified unification model in which the amount of
obscuring material increases with viewing angle and may be clumpy. Such a
scenario, already suggested by differing optical/near-IR spectroscopic and
X-ray AGN classifications, allows for different amounts of obscuration of the
continuum emission in different wavebands and of the broad emission line region
which results in a mixture of behaviors for AGN with similar optical emission
line classifications. The resulting limits on the column density of obscuring
material through which we are viewing the redder AGN are 100 times lower than
for the standard optically thick torus models. The resulting decrease in
optical depth of the obscuring material allows the AGN to heat more dust at
larger radial distances. We show that an AGN-heated, flared, dusty disk with
mass 10^9 solar and size of few hundred pc is able to generate optical-far-IR
SEDs which reproduce the wide range of SEDs present in our sample with no need
for an additional starburst component to generate the long-wavelength, cooler
part of the IR continuum.
