How truthful is ethnographic research?

Having spent many years doing ethnographic and oral history research, I feel that 'proof' and 'truth' are not such absolute constructs. I certainly always check facts as much as I'm able, however sometimes 'official' versions of an event that provide 'evidence' are in fact themselves skewed to present a particular view of an institution, and another 'truth' can be found in hearing the stories of people who experienced the event yet have been silenced by the 'proof' given by the institution. Obviously as a researcher I am aware that people are narrating their story from a particular perspective, but to say that 'proof' and 'truth' can only be proved elsewhere is I think quite problematic.