  The distribution of TeV spectral slopes versus redshift for currently known
TeV blazars (16 sources with z<0.21, and one with z>0.25) is essentially a
scatter plot with hardly any hint of a global trend. We suggest that this is
the outcome of two combined effects of intergalactic gamma-gamma absorption,
plus an inherent feature of the SSC (synchro-self-Compton) process of blazar
emission. First, flux dimming introduces a bias that favors detection of
progressively more flaring sources at higher redshifts. According to mainstream
SSC models, more flaring source states imply sources with flatter TeV slopes.
This results in a structured relation between intrinsic TeV slope and redshift.
The second effect, spectral steepening by intergalactic absorption, affects
sources progressively with distance and effectively wipes out the intrinsic
slope-redshift correlation.
