  We revisit the question whether the critical behavior of sandpile models with
sticky grains is in the directed percolation universality class. Our earlier
theoretical arguments in favor, supported by evidence from numerical
simulations [ Phys. Rev. Lett., {\bf 89} (2002) 104303], have been disputed by
Bonachela et al. [Phys. Rev. E {\bf 74} (2004) 050102] for sandpiles with no
preferred direction. We discuss possible reasons for the discrepancy. Our new
results of longer simulations of the one-dimensional undirected model fully
support our earlier conclusions.
