You might be interested in Anne E. Russon’s book Primate Tourism: A Tool for Conservation?.
It lays out a compelling case, using primary sources, case studies, and research papers, that contrary to being a useful and helpful tool for conservation, wildlife and nature tourism generally do more harm than good. The focus of the book is, of course, primates, but it’s broader than just that and some of the research papers delve more into the issue of nature tourism in general.
There are, of course, exceptions to this generality, and how individuals act makes an enormous difference.
This topic was actually the subject of a presentation I gave at the last International Primate Society conference.