Always been my impression that everything is used as bait.

Personally as a kid pond fishing I would use grasshoppers, cicadas, catepillars, and basically any other bug i can find crawling around.
A Stink Bug is a nice chunky morsel that i'm sure fish of many species would chomp down if given the chance.. I'd think that the structure of its body would make it float ok for awhile too, I dont know that it would generate as much topwater activity as say a big fat grasshopper but still, itd certainly get noticed if fish are around.