If you had a bad mentor for an REU program, should put that on my resume 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.