Harmonica players both suck and blow, and they put up with a lot of jokes, too! Anyone can play a harmonica, but it takes skill and practice to make a nice tune come out of one.
Of course, it doesn’t help if your harmonica is so poorly designed that you couldn’t play it well even if you were a pro, which describes the state of the instrument from the mid-1970s until the early 1990s, when Hohner, the largest harmonica manufacturer in the world, made a single, seemingly small change to its ubiquitous Marine Band harmonica. Hohner’s bottom-line gambit was to slightly enlarge the slots through which a harmonica’s reeds vibrate. It made the instrument’s pair of reed plates cheaper to assemble but the instrument itself virtually impossible to control, thanks to all the extra air that was now being blown into and drawn out of it. Hohner eventually corrected its error, but it took a ragtag group of harmonica customizers and music geeks from around the world to force the 150-year-old German firm to face the music.
Collectors Weekly has an extensive article that tells that story, as well as a short course on how a harmonica works, and the history of the instrument and the blues musicians who relied on it. Link