It can be a long, sweaty session at the gym, and if you go to one without towel service, it means bringing your own towel in your gym bag. Reusing a towel from the previous day without washing it can create an ideal environment for germs and bacteria; after all, it's spent a whole day festering in your gym bag! But how often do you actually replace your towel after use? I've heard anything from daily to "this is gross, but . . ."
So 'fess up and tell me . . .