I hadn't heard of the rag+oxi thing until a few days ago. I tried it, and it did a great job removing a ring around the shoulder from a batch that had been all but abandoned in the closet since april or so. Sadly, the aging did not make this a good beer: it apparently had a wild yeast problem, because there's some unpleasant clove phenol.
Now, when I was rinsing the BB after the wash, some moisture condensed on the walls, and left very sharply defined criss-cross lines where the BB did not fog up. It was really apparent, to the point that I first thought it was actual cracks in the plastic. I believe the criss-crosses are from where the edges of the rag brushed against the wall, though I'm not certain. It was an ordinary terrycloth type rag, nothing especially gentle, but not abrasive by any means.
Have you seen anything like this? I'm a bit worried, especially because of the wild yeast issue. I'm concerned that it might indicate a film that was left behind where the rag did not rub as hard. I thought it might be mineral scale from the Oxiclean, but a Star-San rinse did not get rid of it. I'm not sure what the best next move is, but I really don't want any more of this clove BS.