Spitter - Checking for bad valve stems

Pete Peterson knows how to use spitting to his advantage, especially when it comes to flat tires. Before suffering the embarrassment of a 2.5-hour tube replacement for a slow leak, Pete will first spit on his finger, wipe it over the valve stem and look to see if a bubble forms, citing the possibility of either a bad valve stem core, a loose valve stem core, or a sinister trick played on him by a crafty staffer. Much easier than changing the tube!