"potential signs of cluelessness - look very carefully at the remaining code", since that's also the default

I think what he means (in less sarcastic terms :) ) is that there is no reason not to simply have:

my %hash;
[download]

I'm sure some people would defend variable initialization, even to the default, but in general I think it's more readable to simply accept the default (undef) that Perl assigns. Trust Perl. Perl is your friend.