Considering it's also a surgical procedure, it's not decadent.
Considering most healthy males naturally get a spontaneous erection when receiving an enema, if Steg is a guy, then he'll get a very shocking surprise if he ever receives one.
It's not a medical/surgical/whatever procedure in any decent hospital. It was invented by the guide in Road to Wellville to make cash money. It doesn't do anything for you. It's hard to make it particularly damaging, but it doesn't clean out your toxins or help you lose weight or anything else either. At best it'll free you up some nasty constipation. If a real doctor wants to clean you out, like for a colonoscopy, he'll give you pills that make you shit your brains out. Clean you out from the top down. Even the ultimate powered 'high' enemas will leave plenty in the upper reaches.
Well, it's useful for sex too, I suppose. Anal sex and stimulation, and a fetish, but those aren't medical procedures.
Actually, enemas *are* a medical procedure...but it's not used that often, and the aim is to take advantage of osmosis to speed up the absorption of a medical compound. The intestinal walls being so thin, medicine can be rapidly absorbed into the body through them.