  We show that the clumpy structure of star-forming regions can naturally
explain the fact that 50-70% of GRB afterglows are optically ``dark.'' We also
show that dust echos from the GRB and its afterglow, produced by the clumpy
structure of the star-forming region in which the GRB occurs, can lead to
temporal variability and peaks in the NIR, optical, and UV lightcurves of GRB
afterglows. We note that the detection of GRB ``orphan'' afterglows would
provide strong evidence that the star-forming regions in which GRBs occur are
clumpy.
