Ask the candidate to code a simple program. Check to see if the program works and if they use strict;
in reply to Have you netted a Perl Monk or Perl Pretender in 5 minutes or less?
Avoid leading questions. Ask them to tell you about projects they've worked on, what problems they found most interesting and how they solved them. You may not be able to accurately determine their level of Perl prowess, but you'll get a good feeling for their skill level.
One other thing... Note how candidates list 'Perl' on their resume. Perl, not PERL perl or pearl.
hope this helps!