If you mean CLEAN as in an enema, I would very much doubt it. In fact, other than standard hygiene (daily shower, etc). I can't imagine they would do anything special in anticipation of any type of body worship.

AND... not to lecture but do you really want shiny clean??? Dommes realize that most subs absolutely love to see, smell, feel, and taste a Domme in their most natural state. If your Domme allows this and presents a dirty ass (in any context) for you to worship that likely means she thinks a lot of you to give you that special treat. Learn to savor her smell and taste - become addicted to it and your level of worship will dramatically improve.