Can anthropologist really study a culture, or do they invariably alter it?
This is certainly something that is discussed among anthropologists. Some feel that the very presence of an anthropologist or any type of researcher changes the way people interact. Most anthropologists seek out a few informers to give first hand information and answer questions. Among tribal societies, this informer is usually someone that has experience in or knowledge of Western customs. We rely on informers to tell us of cultural taboos, rituals, and symbolic communication. I can tell you from personal experience that the best way to learn about someone is to listen to what they have to say, but you have to maintain your objectivity. Personally, I think you can learn something by observing the way people interact with outsiders. While some just observe from afar and only really interact with their informers.
