From personal experience, I can report that ice water enemas can be VERY PAINFUL. 😮 Then, I guess, it's a matter of personal preference as to whether that's a nice thing (or not) ! If you want to punish someone with an ice water enema, you can certainly make them BEG to stop - it can be really painfull !
Very cold water can also be quite interesting. Cold (not ice) water enemas are medically recognized as a way to bring down core body temperature, as in the case of high feaver, and I have tried them myself for that, and it does indeed work.
Sometimes after a very strenuous workout or on a very hot day, I will take a very cold water enema, and it rather quickly cools me down and ends the sweating.
For a very interesting experience, try taking a series of cold water enemas (2 to 4 quarts), holding each about 10 minutes before evacuating. By the third enema you will have reduced your core body temperature enough to make you shiver and quiver all over. It's quite a feeling. Quite likely you will not much care for this - but it is a very interesting feeling. A series of very cold water enemas makes and interesting punishment. After you've had one, the very threat of one may be an effective punishment!
Like lots of things, when overdone you probably can DO HARM - SO, as they said on Hill Street Blues: "Be careful out there"...