Great answers above!  Here is my (California) take on this.

We run all owners 10 years back for liens & judgments.  If there is a purchase money mortgage, and the buyer only got a lender's policy, then the title company may not have run the buyer for liens & judgments.  An insured PMM (residential) has priority of the buyer's liens, so many title companies won't run the buyers.  That's why we always do 10 year searches and not just start at the PMM. 

Once there is a re-finance then the new title company should be running the owners back 10 years for liens & judgments, so that should be a good starting point for liens.  But I have seen too many times this was missed, and best practice is to always run all owners back 10 years to be safe.