I have volunteered regularly to run children's summer English camps in rural China. The point of these camps is mostly to give the kids an opportunity to have fun and learn some English while they're at it, because such nice opportunities simply don't exist where they are. Camp counselors in North America for summer camps don't go through extensive counseling training either. The bar for such volunteer activity is lower, but the bar should be much higher in other cases. Here are some things I've learned about non-profit organizations that are well-run.

Firstly, well-run organizations want to maximize their ROI. The volunteers usually fundraise for donations or pay out of their own pocket to go on these trips. Essentially, these funds are revenue for the organization. That revenue must then be invested into their business, as their purpose is not to make a profit (hence non-profit), but rather, accomplish their goals to make the world a better place in their specific way. As such, a good organization will get tourists who are qualified to do the work that needs to be done.

The organization with whom I volunteer has multiple programs in medicine, agriculture, construction, education, and local skills training (for local professionals for the above categories). They ensure that the people who are volunteering are qualified to do their work. For example, for my most recent excursion, I couldn't stay the entire camp, so they asked me to run some sessions with local teachers instead, since I had so much experience volunteering to teach their kids. I prepared some lessons and explained to the teachers that I was not a professional teacher like they were, and that my teaching wisdom and experience only consisted of basic theory and volunteer experience. I made it clear that I was not qualified to teach them about teaching. Instead, I focused on professional skills that I brought over from the corporate world. We had sessions on conflict resolution and negotiation tactics using concepts developed by Max Bazerman at Harvard, the Behavioral Change Stairway Model at the FBI, and discussions about conflicting cultural worldviews and personalities, the basics of which are taught in many corporate seminars. I also focused on leadership styles, motivation tactics, and decision-making strategies. My sessions were very well-received and I received lots of thanks from the teachers, as well as a round of applause at the end of my time there.

This organization never asked me to do anything like surgery, building repair, etc. They did ask me to help out with some computer stuff now and then. For their medicine, agriculture, and construction programs, they made sure to bring in only qualified people. Full stop. The organization had a relationship with the local government and had gained respect of the local government because they did things properly. That's the way it should be. When you're a non-profit, don't do anything that will waste the scarce dollars you have been given.

Secondly, it's true that your impact in these countries is small. But it's like the story of the kid who saved the one starfish. The man comes along and asks the boy why he saved that starfish, what difference does it make in the face of so many starfish dying on the beach? The boy thinks and says, "Well, it made a difference for that one." I still keep in touch with the kids I've taught. The Internet is wonderful today and makes this easier than ever, except in those locations where the situation is so dire that you take Bill Gates's attitude of choosing to fight the malaria over getting the Internet up and running. Overall, I know that the kids are impacted on an individual basis because they keep in touch with me, still call me Teacher, and talk with me about things. The people in these communities appreciate that someone took their time and money to go and help them, if what was provided was helpful. Again, that goes back to the organization making sure that the money and effort is being spent in a way that maximizes ROI. It's the same in business. You don't tell a recruiter to do the bookkeeping, you get a bookkeeper or accountant for that. It just makes sense.

Thirdly, these trips have value in that they work as vision trips. A percentage of volunteers will go on these trips and have their eyes open and their thinking changed in such a way that their life goals change. Those people are the ones who will go into this work full-time and throw away the nice cushy jobs in the first world. Those people are also often the ones who can afford to do it because they've been working nice cushy jobs in the first world for a while, so they have the savings to make it happen for some time until outside donations can take over in terms of funding everything. If these trips don't happen, a huge recruiting channel for these organizations for long-term workers completely disappears. These organizations prefer that these trips be available for people from every generation because you don't know where you'll find the people who will have the switch turned on inside themselves, and you don't know which people will have which kinds of support networks that would be willing to help fund this lifestyle. This third factor is possibly the most important reason why these trips are a good thing.

The goal to have a locally-run operation staffed by locals is an important one. But it takes time to get there, and these trips are a part of the process to get there.

edit: clarification