I was introduced to enemas, and learned the difference between Fleets and the "real McCoy" while hospitalized at the age of ten in 1960.
At the time, I got no pleasure from the process, but at the first awakenings of my sexuality a few years later, I definitely recognized that a quart or more from a bag or irrigating can was a lot more pleasurable than a few ounces from a squeeze-bottle, so I began experimenting on my own using an old Faultless combination apparatus my relatives thought they'd thrown out.
I've used occasional enemas for both cleanliness and pleasure ever since. During my college years I had the time to do a little research, but you had to dig deep. Enemas aren't mentioned at all, for example, in Dr David Reuben's book "Everything You Always Wanted to Know about Sex, (but Were Afraid to Ask)", which was popular during those years.
All that began to change around 1972, when the first of the "Special Preference" letters appeared in Bob Guccione's Penthouse, and I suspect this was the single most prominent factor in bringing klasmiphila out of the closet, although the discovery of some work by Prof Wilhelm Stekel, a contemporary of Freud, proves that the practice has been studied for a lot longer.