It is the abstractor's job to report which liens, mortgages, etc. encumber the title to a property only. When I was doing title searches I normally dealt with the issue of tax liens, mechanic's liens and other time barred encumbrances as follows:
 
     1.   If there was a release specifically addressing the lien, the lien was not listed in the abstract as an encumbrance. 

     2.   If the lien was not released or not expired it was listed as an encumbrance. 

     3.   If the lien was not released, but there was some question as to whether the lien was expired or renewed, the lien was listed as a potential encumbrance to the extent that it was not expired or otherwise released, and a notation was made in the abstract that further inquiry should be made as to the current status of the lien.

It is not the abstractor's  function to make judgment calls in questionable situations. Remember, you are only getting paid $50.00 or less for a current owner search, possibly driving 25-30 miles to a town hall at your expense to perform the search , or possibly you are one of the abstractors being asked to reduce your price and include the cost of the copies in return for nothing from the client. Why should the abstractor incur the liability of making this determination? Scott is right. Someone else is being paid the big bucks to make this determination. Let him know the potential encumbrance is there, and let him earn his fee.

Before I issue a title insurance policy, I want to know the current status of potential problems rather than run the risk of insuring over a problem. When I am confronted with the problem of a possibly time barred lien, I list it as an exception to coverage until the property owner produces a copy of a duly recorded release.

When you can have the absolute release of the lien why rely on a time limitation which may or may not mave been renewed, the renewal or release may have been recorded out of the chain of title, or which may have been tolled (extended) for some reason. Even if it has not properly been tolled, arguments can be made for it which require a ruling of the court, and you have to go to the trouble and expense to defend. It is a drop in the bucket to the taxing authority if they are ruled wrong. I know of someone locally that got into a dispute with the IRS. He appealed all the way through the courts, and finally was driven out of business only to have the IRS finally concede that he was right.

I am very pleased when an  abstractor has brought a potential problem to my attention. It gives me the peace of mind of insisting on a release of the lien.