This is very interesting, and the responses were all great.
I like to think I'm a 5, but like Legato345 sometimes I'm like both a 1 and 10 at the same time. The feeling that an enema gives in the physical sense is most pleasurable when given/taken slowly and with compassion and caring and soothing in the process.
From a psychological aspect, I think of expelling an enema as more than just emptying the waste. It's also emptying out negative feelings and emotions such as stress, anxiety, tiredness, worry, fear, apprehension, and so on.
When I was in college and staying in a dorm, there were posters about the dorm that gave hundreds of ways to relieve anxiety and stress over impending course exams. Interestingly, one of the ways was through the use of "high-volume enemas". I would never have expected to see that in a college dorm, but there it was in black-and-white. I would imagine some girls did try it, but I seriously doubt any boys did.
In the very few times I was fortunate enough to engage in more intimate enema play (vs role-play), the focus was not on providing just the physical pleasure of enemas, but also encouraging in the psychological aspects as well. That is, I encouraged the release of negative emotions and feelings during the enemas that not only brought on total relaxation for the receiver, but culminated in an intense and very pleasurable release towards the end.
In role-play lacking intimacy, the receiver (myself included) would likely score closer to a 1 since it would be more physical than psychological; in intimate play, closer to a 6, or even an 8.