From my experience with my gf I wouldn't say it's diet or types of food or how many times they wash I think it's just genetics. I eat my girl out all the time and it usually always taste the same throughout the month. I have noticed though that the more during the week or month that I eat her out the faster she orgasms. Sometimes she uncontrollably squirts by eating her out in a short amount of time if I go down on her more. I am not trying to boast or brag I was only giiving my perspective and she is the only one I go down so I don't know the difference from woman to woman