It's always best to have the sewer lines inspected before you buy a home. Even small repairs can cost thousands of dollars. Aside from the foundation and roof, sewer lines are one of the most expensive repairs you'll make out of unexpected necessity.
Sewer scope inspections involve running a camera down through the main drain of the home to look for blockages that could cause backups. But, more importantly, it will tell you if you are up against a very costly repair bill or a simple preventative maintenance clean-out. It will also reveal if any repairs have been made.