Appreciation post: A messy kitchen remodel in Akron taught me to always check the subfloor first

I was helping my buddy with his house last month, pulling up old vinyl in his kitchen. We were ready to just lay the new plank right over it. His neighbor, an older guy who used to install floors, walked over and said, 'You boys even look at what's under that mess?' We peeled a corner back and found a huge soft spot from an old leak. Would have been a nightmare in six months. Now I pull up a full corner in every room before I even give a quote. Anyone else have a simple check that saved a job?