Unless you’re into fisting, I really don’t see any reason to douche. Healthy diet and regular bowel movements are all you need. If your stomach is upset and you got the shits, enema isn’t really gonna help at all since it has a laxative effect.
Also, if a man can’t deal with seeing a bit of shit on his dick (on the extremely rare occasion this had happened in my experience), then in my books he’s not man enough and I have no reason to see him again.
I had this one time when a fairly macho guy turned to full diva mode when he saw the tiniest amount of shit on his dick. I was like “yeah, you’re fucking an ass. Shit comes out of it. Well fucking done, mate, you discovered hot water” and told him to get washed, dress up and leave.