Alright, I want to get in on this conversation too. I have two bits to chime in on.
I was in Malaysia in July for the VIFA Asia Open. Last year, my friends went and came back with a story about a UAE guy who would yap and yap. And this time, I saw him, met him (I'll leave out his name), even had dinner with him once. Most years, he wins the Open Singles at this event - so he's a skilled player, but he has a reputation for getting real chatty after every ball. He said this is just part of his game, used to get into the heads of his opponents. His game isn't the same without the trash talking. Yes, he carries himself as an over-confident / arrogant person in general (that's just his personality), but he's actually (as far as my limited interaction with him) not a bad guy. But I can see how playing against someone who can't / won't shut up will rub people the wrong way. He was fairly quiet when I played against him in Open Doubles, but maybe because he didn't need to talk much - his partner was killing me up front. Actually, I think he made an effort to tone it down this year. But he was more chatty being a spectator watching his UAE mate play against one of the top Malaysia players. He would stand at the side, and make comments each time his friend put in the ball. I should note that everyone who's played in Malaysia for this event knows this guy... he's been joining for 8 years. So they know what to expect, but I can tell he still pisses people off... a lot. And when it comes to young players with egos, sometimes these turn physical.
Trash-talking is just a natural part of competition. I don't think it's unhealthy, but it really depends on the level of trash-talk. When I play with friends, we'll have friendly trash-talk, usually coupled with a friendly chuckle or "hehehe". So it's light and easy.
More about attitudes. Since I'm originally from Vancouver, whenever I go back home, I try to drop in for some play. I haven't played too many places actually: Vancouver, Taiwan, and San Jose. But the Vancouver guys as a whole are the worst as far as attitude. Maybe just a few rotten apples spoiling the barrel. I dropped in for a DYP after a few years away and there was a scuffle and arguing about people cheating. Lots of poor sports who take the game way too seriously. Then I went on their message board and saw people complaining about how they don't like the other person, how once one person choked another person, how one person wants to punch another guy in the face, etc. I'll still go, just because I love playing foos, and because I like the challenge. But this is something that SERIOUSLY turns people off from the sport. No one wants to be a part of that kind of dysfunctional family. Maybe the locals are happy with that dynamic because they know the history, they know each other well, etc. But as an outsider, I can't tell how serious these arguments are. And this is a factor in the stunt of the growth of foosball in Vancouver. The promoters (like the Tielens) know that too, but they can't do much about it.
My two-cents.