A customer in a 2005 Civic swore his engine was shot, but it was just a $12 vacuum hose

He came in yesterday saying the car was shaking and running rough, ready to junk it. I popped the hood and heard that classic hissing sound right away. Found a cracked hose behind the intake manifold, replaced it with a piece from my kit, and it idled smooth. How often do you guys find a simple vacuum leak that someone thought was a major repair?