During my hospice work I talked to one elderly woman who thought it was great I was going to be a doc, etc. until I mentioned DO. Her dislike of DOs stemmed from the fact that her father was an MD, who like most MDs in the 1940's, was sent sent overseas during the war. DOs at that point were not allowed to serve as docs in the military and so ended up providing lots of care on the homefront. After the war, many patients stuck with the DOs, creating some bad blood with MDs who arrived home to find their patients gone. This is mentioned in some of the DO history books, but I don't really know how significant a trend this was.