Are you talking about douching? Pretty sure that's bad for you
Let me explain the difference between douching and cleaning.
Douching can involve soap, or any other chemical substance that is normally used to clean external living tissue, i.e. skin.
Cleaning is as simple as directing a shower hose towards the inside of your vagina. I was seeing someone last year who had a snake-like hose that could be attached to a shower nozzle and hung about knee-length, which she used for that very purpose. Never had an infection or any other problem and her hygiene was excellent.
The idea that cleaning your vagina is in any way unhealthy is like saying cleaning your mouth or your rectum is. Complete myth. And for guys who might be unfortunate enough to find themselves within breathing distance of something as moist and fluid-producing as a woman's genitalia, I sure as hell hope most women don't believe in it.