The easy answer is that many people that play the harmonica are extremely annoying to those around them and they play and all of the wrong times.
Last night, I saw the human embodiment of every trait that I loathe in a harmonica player.
- They play while sitting the audience while other people are on stage performing. The band was on the stage. There was another harmonica player up there playing his ass off, while some moron was sitting at a table playing along with the band. Of course, he was totally out of key and playing a very high pitched harmonica. It's almost always been something that they has to be special ordered like a Hi-G dog whistle. Unfortunately, it isn't high pitched enough that only dogs can hear it. Everyone within distances typically covered by a restraining order could hear him whining on that damn harp. Nothing annoys me more than this.
- This is a sub-point to point 1. They park their lazy ass carcass next to the best looking girls in the bar, so when you are scoping out the ladies you can't help but see them in the midst of their little performance. They sit there, trying to chat up the ladies and saying stuff like, "Hey baby, check this out. I can play that." before they begin another alcohol fueled harmonica solo. Of course, some poor sap is onstage playing.
- Another sub-point to point 1. You can't escape them. Ever. You go to the men's room they are in there playing to take advantage of the tile walls and the echo, so they can sound more like a classic Excello recording. You go outside for a breath of fresh air, they are out there attempting to blow their brains out, but they never seem to succeed.
- They rush the stage and attempt to wrestle the microphone away from whoever is up there playing. This basically says two things. First, they think that the person that is playing sucks. Second, they think that they can do a better job. In most of these instance, neither is usually true, but you can't tell the person that. They won't listen, because they are busy playing away.
- They are running around all night long like a damn lunatic, playing that blasted harmonica and then when they finally get their big opportunity to get on stage and play with a good band, they run for the door like the building is on fire.
- Finally, poor grooming and personal hygiene.
Why does this happen? Who the hell knows. I suspect it is because harmonicas are cheap. I don't remember who said it, but the basic idea is that the first harmonica someone purchases should cost several hundred dollars to weed out those kind of people.