This is true of Duragilt, but not Permadent.  Permadent starts with a
 pronounced, raised,  cell impression that is wax coated.  I have scraped a
bad comb off on several occassions after 3 years of using Permadent and the
bees always will rebuild.
After the bees chew off the wax coating on Duragilt all that is left is a
smooth sheet of plastic.  Permadent is also less labor intense to install
than Duragilt as it is a rigid sheet that just snaps in the frames without
the fear of damaging it.