A few points regarding the responses:
1. Money. Is that really more than what you would be spending on a TBS? I don't think so.
2. Host families, from what I understand, need to be approved.
3. Truly troubled kids, i.e. hard-core drugs, suicide, cutting (that's really not that big of a deal, I've had people do it to me. It's a cross between a pain/pervert thing. Trust me.): I was depressed and had made two suicide attempts. Some time abroad definitely would have helped that. I know I am arguing the hypothetical here.
4. Time abroad and things will be exactly the same when they get back: Is that any different than a TBS? The only difference is that they are in a positive environment where they learn, not brainwashed into a false sense of well-being where they have no social skills coming out. Besides, I have a suspicion that a trip to another country is going to help turn a kid around a lot better than a TBS or doing nothing at all.
5. Academics: As I said before, there are
cultural exchange programs (see my link in the initial post) that do not require knowing the native language or a high GPA. Max 2 months in the summer.
6. Sending your kid away is program mentality: Even the most troubled kid needs space once in a while. You may consider that you are "getting rid of your kid", but the kid is someplace positive. There is nothing wrong with needing space, just as long as the desire is not misplaced or abused.
7. Kids won't want to go. I agree to that possibility wholeheartedly. I myself would possibly be reluctant. This is where positive manipulation can come in. Sell your kid on it. I'm still working with this one. Even though there were things that were truly fucked up about me as a teen, there were still places I dreamed of going. Especially to get away from my parents. And like I said before, their same group of friends will be there when they get back. And hopefully, they will come back with pen (or email) pals after their experience.
8. What host family will want a troubled kid?: Who says the kid is going to be like that when they arrive in their host country? Give them some credit. Maybe they will, maybe they won't.
9. Yes, I agree, Amsterdam is off limits.

Despite the fact that nothing goes better with drugs than whores.
How is being 17 relavent to your original point when you stated that the parent should wait till their kid is 18. If the kid is 17 I still say they can save up their cash and pay for their own traveling. I was traveling all over the place, alone, by the age of 17, though none of it was out of the country. I paid for the majority of it myself.
But not every kid is going to have as good a work ethic, gookie. Does that mean they shouldn't have the opportunity? There are lots of "non-troubled" teens who do foreign exchange and don't have the money for it.
Now if somebody could come up with a good idea on how to get the parents and kids talking to each-other and getting along... that would be impressive.
Problem is, psy, nobody is trained to be a parent. There may be books by idiots like Dr. Phil, but there is little truly useful things out there on how to work and communicate with a teenager who is an asshole, which is their job. My guess is that the best go-to person for this would be a GOOD schoolteacher, such as my best-friend. How to get along with a teenager? Good luck with that. That's like the holy grail of (as of yet) unanswerable questions.
My final point is: So what if the kid comes back and is still a sourpuss. At least you tried, you know? Couldn't hurt. Like I said, cheaper than a TBS or wilderness.