I don't know if it was because I have one of the lower grade lenses, but I've ignorantly rub the inside of my Crowbars many, many times with the goggle bag to clean or dry them, and nothing of the sort has happened to me. I'm not sure if I've completely wiped off all of the anti-fog or if there was none to begin with, but my goggles don't have smears and I don't have that bad of fogging in them.