To answer Mandy's original question, I have never given an enema to an enema virgin and had that person turn out to be absolutely in love with enema.
That doesn't mean that I don't think it could happen.
As has already been explored by others here, one's attitude towards enema has a very complex base; being tied in many ways to a person's upbringing, what they have been taught about handling their body, how they have been 'treated' for various conditions, as well as their personal physiognomy (did I spell that right?).
I think it IS possible to 'discover' a person's tendency to enjoy enema, but I also believe that it is possible to 'train' a person to enjoy them, provided the basic physical mechanism is operational. When I was being raised, my natural anal sensitivity was enhanced and 'polished' by the enema experience to which I was subjected to the point where I enjoy them, as openly as I dare. The environment was that it was 'normal' for a parent to give them to a child, as many as the parent might feel was necessary. My wife knows my enjoyment, but I haven't shared it elsewhere, except for here, and with the few who have been willing to chat about it with me.
And I believe that it (enema affinity) could be a lot more common than it is, and is not because of the attitudes of parents. People that come out from under the shelter of their childhood covering sometimes discover this for themselves.