In a recently released draft paper, Lee Petherbridge, Polk Wagner, and I discuss the results of a study in which we empirically examined patents that were determined to be unenforceable due to inequitable conduct and compared them to litigated patents. We report evidence that unenforceable patents are different from litigated patents. Unenforceable patents have significantly longer pendency, more parent applications, and contain more claims. Unenforceable patents also cite fewer U.S. patent references. Surprisingly, we found no evidence that patents with foreign inventors are more likely to be unenforceable and no evidence that the subject matter of a patent associates with an inequitable conduct determination. Using these observations, we hypothesize about why inequitable conduct happens, how inequitable conduct relates to patent policy, and what - if anything - practitioners who are concerned about an inequitable conduct determination might take as potential warning signs.