reporter's "simple assumption" (subject to) sale goes awry

[Steve Babiak]

The biggest newspaper in Phila - The Inquirer - recently ran a story from a reporter who was having issues 14 years after he agreed to allow a buyer to acquire his property by a "simple assumption" of the mortgage; sounds to me like a "Subject To" transaction.

http://www.biggerpockets.com/links/1640-a-cautionary-tale-about-assumed-mortgages-phila-inquirer

So, what measures should the "Subject To" investor use to ensure that such troubles do not arise down the road?