Huh. I actually hadn't considered this issue before. I'm using pretty much the same kind of towel. Looking inside, it does seem like the onaholes are a bit scratched up, although I can't tell if that's how they arrived, or whether it occurred through drying or normal use. In any case, it doesn't seem to have affected the actual sensation very much, and most people recommend drying with a microfiber towel, so I would suspect it's not too much of a problem, unless the sensation becomes noticeably worse? I suppose to be really accurate you'd have to buy two of the same onahole and compare them after extended use.