I did an REU research program in my undergraduate college career. However, I had a bad experience because my mentor was not helpful and was very condescending person. I was told too that you worked closely with a mentor or grad student before I even started the program, which obviously did not happen. The program was disorganized that even the grad students did not know that they were suppose to help or guide the undergraduate students in their research, and they were also not helpful. So it was like me doing all the research by myself with no help or guidance. If you did not have a good experience in the REU program, would you still put on your resume in order to get into grad school?
Yes, I would include the experience on your resume. You gained research experience. Even a bad REU almost certainly taught you more than an unrelated experience or job. If the topic comes up about your REU experience during an interview, I would talk about what you learned in a positive way. For example, you appear to have learned about the importance of organization during research.
However, I would not list your mentor as a reference. Perhaps you could list on the graduate students you worked with during the REU. Also, do not worry about a lack of publication or presentations from your REU. In my experience as a REU participant and now an REU mentor, few projects result in publications even from well run programs and presentations are largely a function of your program and home university.