I'm publishing one of the tricky questions I ask when I interview people for Perl developer positions.
"Tell me about
Why it is a bad question: nobody (and I mean, really, nobody) ever uses these operators in scalar context. The only way to really know them is to have literally learnt all the perlop by heart. I once did it because I studied Perl offline and the information to feed upon was very scarce.
Why it is a good question: it allows me to know whether the man understands Perl contexts in 30 seconds.
IMHO, this question brings more grief than benefit so I hereby decide to ditch it. Hooray!