I use scrub all the time.
/opens /etc/pf.conf
/closes
See?
Like they said, depends on harshness of product. Some of it's really gentle and it's fine to use even if you're one of those high-maintainance asshats who showers 3x a day (no, I'm not ranting at anyone I know, really) but others are powerful enough to remove driveway grease stains ("Pimple Farmer Strength") and would slow eat your flesh off of used too frequently.
Anyhow, it's all about following the directions on the back of the bottle.
- M4H