One respondent said his music teacher told him, "always listen to recordings first. Don't attempt pieces you have never heard. Your time is too valuable to waste." [ ? ? ? ]Two or three others indicated they NEVER play a piece they've never heard, and in fact, would avoid such a situation.
Reply to "The Hammer" --Even if I grant you all that you say, where you explain benefits of listening to a recording first, I guess my point is -- does this ALWAYS have to be done?
On the other hand, listening to recordings (escpecially for advanced/professional players) is no must. You can easily play a piece never heard before - why should you not? It can also be fun to try it on your own, to think of possible interpretations for yourself. But if someone other can convince you, that his playing is "better": why be so stubborn and stay with your playing? Just because it's yours? Do you want to be a better musician or a better narcist?