Stink bombs, or "malodorants," have actually been used by the military as far back as World War II. That's when American scientists developed a stink weapon nicknamed "Who Me" for use by the French resistance against Nazi soldiers. The idea was that French resistors could walk up to German soldiers and spray them with poop smell, thus embarrassing them, and, after an unknown second step, the Nazis would lose the war. As you didn't learn about this in history class, it's probably clear that this tactic didn't work.
As members of the French resistance discovered, if you try to spray a chemical mist at another person while standing close by, a lot of that s**t is going to get on you. The sprayer ended up smelling just as bad as the person being sprayed, and it took about two weeks for everybody involved to realize that "Who Me" was a dismal failure.
High-ranking Nazis spent all day sweating in leather trench coats, rendering the spray redundant.
DARPA's XM1063 bomb resolved most of these issues, but another point that has raised eyebrows here is that you need to be ridiculously racist in order to get poop bombs to work, and not just the OK form of racism that involves French people. Diet, culture and lifestyle choices mean that different populations perceive many smells differently, and if you want to create a stink bomb, you need to profile members of the target population and then build a weapon specifically for them.
We're not going to tell you what a bad idea it is to develop racially profiled weapons, since we're assuming that you were all awake for at least five minutes during your high school history class. But this is pretty much why the perfect stink bomb has evaded the U.S. military all these years -- they're actually not racist enough to have figured out how to develop a weapon that's sufficiently effective. But for all the reasons why a war effort might fail, "lack of racism" is probably one of the most socially acceptable.