Oddly enough, I ended up having a conversation with my Mom about douching after I made a joke about those gawdawful Massengil commercials. Lucky for me, I got the whole "throws off pH balance/makes you more susceptible to yeast infections" rundown, to say nothing of the (TMI to my 12 year old mind) speech about how offensive it was to imply that there's something wrong with a woman's body that would need to be covered with perfumes, and if there's ever a strange smell or itch or anything down there to let her know because that means you need to go to the doctor. *whew*
So, in short, vaginal douching? No, except for a vinegar/water/tea tree mix I used once to get rid of a yeast infection (which did actually work for me ... I used a 50cc syringe & rubber tube to administer twice a day for a week).
Anal douching? With plain warm water before anal sex, yes, absolutely, every time. Feces? Just a leeeetle teeeeeeny bit less sanitary than vaginal secretions.