Since I collect some things that originally were cut off boxes or packages (Wheaties, Kahn's, etc.), I've considered your question before. I trimmed a few ragged-edged cards at first, but when I mentioned this to several collectors, it was clear some were offended by what I did. As a compromise, I simply "trim" the borders straight (thanks to Photoshop) on my website and leave the originals alone ...
My collection:
http://imageevent.com/ccmcnutt