Sure, while most people drink coffee as a caffeine delivery mechanism, some people actually like the taste and don't want to get the jitters. They are crazy, but hey, different strokes for different folks. For them, if they really want to make sure they got real decaf, there's D+caf strips.
These little strips allow you to tell whether or not that smug jerk at Starbucks gave you what you ordered. Simply dip the strip in and it'll change colors if it detects more than 20mg of caffeine. Then you can throw that hot, caffeinated coffee in the barista's face and demand decaf, because you sure don't need to become any more high strung.