Liens are filed for many reasons and are usually considered adverse.
Federal, state and local tax liens are filed by government taxing agencies asserting unpaid taxes. Mechanic’s liens are filed to secure an interest in a property by unpaid contractors. Homeowner’s association liens are filed for failure to pay common area costs. Child support liens exist in many jurisdictions are filed to prevent delinquent parents from selling a property without first satisfying their court ordered child support obligations.
But, are all liens adverse? The answer is no.
Researchers should keep an eye out for what are known as special tax or assessment liens. These are liens that are placed against all property in a particular area -- usually to pay for a voter-approved project like a park or highway repair. They do not indicate a tax delinquency, just that a new tax is being assessed on a property. A clue that you have stumbled upon one of these: they typically run into the hundreds of pages while most adverse liens run to no more than 2-3 pages in length.
Here is an explanation of a an special tax lien that exists in the Monterey Pensinsula Regional Park District in California to give you more of an idea of how these work.