I followed the same path as hdsouza and agree with his comments. Login, filter, diff, and analyze. I pull the new filtered notes, analyze, and buy any good ones. And I'm not getting the best notes by any stretch of the imagination.
I think you could answer this question by trying to buy notes from yourself. Select one of your own notes to sell. You already know the noteId, orderId, and loanId, and AskPrice. Put it up for sale at a high price, and immediately try to buy it- you should succeed. Now put it up for sale at increasingly lower prices. At some point, you might find that someone buys it before you, even though you knew the details in advance.
I'm planning on trying this test soon. Would be interested if anyone else wants to try it too.