In Colorado, the standard Contract to Buy and Sell Real Estate provides that the title to the property will "...be conveyed free and clear of all liens and encumbrances..." Once you are under contract you will be provided with a committment for title insurance from a title insurance company. Schedule B1 of this committment will outline all of the liens and encumbrances to be removed at closing as a requirement for the title insurance company to actually issue a title insurance policy. If the title insurance/escrow company conducts the closing, they will make sure all liens are paid at closing since they are insuring the title.
A reputable title company can confirm that liens have been removed. As a buyer, you want to insure you and your attorney have reviewed the title commitment on any property you wish to purchase in order to confirm there are no liens.