ImTheCaptain
I disagree with you
"Pilfer through" is a pretty common phrase......34,200 hits on Google (as is pilfered through and pilfering through). I imagine in that context it means looking through something with the intent to steal or maybe to steal information about what is in something.
https://www.google.com/search?q="pilfered+through"&ie=utf-8&oe=utf-8#q="pilfer+through"
i'm not impressed that there are others who are dumb enough to misuse a word