It's not the dolphins. It's the people who study them. The whole field of people who are interested in dolphins are slightly weird. It doesn't take much googling to divide into some special camps: the protesters, the romantics, the healers, the fun-seekers. The noise makes it difficult to find useful information on the web.
With that said, hopefully this article about dolphin basics will succesfully encapsulate some hard scientific evidence in an easy-to-read format. And yes, I found peer-reviewed papers for all of the claims that are in there.