There's more than one way to fix a leaky valve. In this particular instance the homeowner duct taped a sponge to the affected valve. As it leaked, the water dispersed through the sponge and evaporated, thus preventing a leak to whatever lay below...
Special thanks to Trent Martin at Mr Rooter Plumbing for providing the photo and story. Trent fixed the valve properly. I give you honorary HomePro Home Inspectors status.