It's difficult to critique a moving target, as I am not convinced that the Brainbench perl 'quiz' I did in 2007 bears any resemblance to that which you have experienced, and by the sounds of it - there are several perl exams.
From memory (rusty) it dealt with more of the basic language than idioms or patterns prevalent in perl. I do recall skipping a couple of questions that I regarded as un-answerable per the text. I've also undergone some home-grown perl tests from various employers which generally have a similar focus on depth of understanding of the language and syntax. My favorite question from that pool was "How would you parse a CSV input?" , the answer of course being.. "Don't!, use Text::CSV and get on with your life."
I can't believe it's not psellchecked