I'm female, and I find myself asking the same question. I used a fleet once, when I was 19, in preparation for anal sex with my exhusband. I dreaded the stupid thing, and was not happy about it. I shoved the nozel in, and as I started slowly emptying it's contents, I noticed I was dripping. I thought I was leaking enema solution, but it was something else. I was really engorged too. I was alone, thank goodness. I felt like a total freak. I was enjoying this. I really didn't start playing around with more than the fleets for 5 years or so, and still do them mostly by myself. I ask my husband to help, as I claim it's for anal sex prep, he hasn't caught on that more than half the time he helps, anal sex hasn't followed.
I did tell him recently that for whatever reason it felt really good to have warm liquid gushing into my rectum. And when I was preparing a small coconut oil injection, he grabbed it from me and said he was giving it to me.
I can't answer your question though. It just feels good. The fullness is really a turn on. For me, I get extremely wet and very engorged the minute the flow starts. It's really hard for me to explain, since I have Crohn's disease, and I dread anything that resembles diarrhea and the cramps that go with it, since it's a part of the disease that has attacked me with a vengence.
What would make it even more of a turn on for me is to have my partner involved in the process. You know, the coaxing, massaging, encouraging me to take more. And the phrase "good girl" works wonders on me, though I haven't heard it since my last marriage. I think it would be all the more enjoyable to have my husband give them to me, not under false pretenses. Then I wouldn't feel like I'm some kind of dirty freak. Sorry for not answering your question. And for the record, I never had enemas as a child. The first one ever was the fleet at 19.