A permit check should always be done when buying a home. Here's some great advice from Dan Phillips, a Realtor in Eureka, CA. Thanks Dan! Please go leave a comment on Dan's original post.
One of the suggestions I make to buyers is to check with the Building and Planning Department to see if there are any "open" permits on a property they are considering purchasing.
An "open" permit could prevent another permit from being issued for the property: say to replace a roof.
If there is an "open" permit on the property, one in which the final inspection has not been completed, the clients could be subject to big expenses if they purchase the home.
In order for an inspector to check the quality of plumbing or electrical work, new drywall may have to be removed. This can be expensive. There may be additional permit fee's because the inspections were not completed on time.
My experience in this area has always been that the Building and Planning Departments are a buyers good friend!