It  is  really important to find out historical facts about the property ,, the reason behind sale of property, house, or office, It is necessary to find out the life of people led by previous occupant.
Many people generally sell their plot due to sudden mishap in their life such as bankruptcy , death, suicide, persistent sickness, or other mishappenings, such kind of plot are not considered auspicious, these plots are installed with negative vibrations and energies that can  even make life of new owner miserable,,,
1. Buying a new plot is always considered ideal option. 
2. According to Vastu yet for any reason existing property is being purchased , its important to find out the history of the plot, if it is displeasing then you have to nullify negative vibration through  Vastu remedies