Josh, my experience with the alter-ego/nominee liens is where you need to show either there was a legitimate purpose for the transfer, or it was not transferred for the purpose the IRS says (usually to avoid collection). For instance, it was transferred several years before the first liability arose. It is really fact specific though. Do you have one now, and do you believe that it was filed improperly? Unfortunately to challenge these it usually requires the taxpayer to go to federal district court in a “quiet title” action, which gets very expensive.