In a thread about this, earlier, someone stated that case lube would gunk up the polishing medium in a tumbler, and therefore that lubed and resized cases should not be cleaned that way. The medium was claimed to ball up and stick together.
Scientist that I am, I just had to try it to see how bad it was. I started by tumbling the cases in ground corncob to clean them up after firing, as is my standard practice. Then lubed these clean cases with RCBS Case Lube-2 and deprimed & FL sized them. Then the experiment began.
Surprise!
When I put about 180 cases of resized 7.62x39, all with case lube on them, into the tumbler after FL sizing them, turned the tumbler on, and left it for an hour or more, the cases came out smooth, not lubed at all, and as far as I could determine, ready to prime, load, and fire. The cleaning/polishing medium used was ground corncob, a batch which I have been using for a couple years with good satisfaction for case cleaning/polishing. I had thrown in perhaps a dozen 1x1" gun cleaning patches along with the corncob, as I had heard somewhere that these absorb the dirt and gunk from the cases and the medium stays cleaner. These patches have gone from white to quite gray over the time they have been in with the medium. The medium has seemed to stay clean and effective.
Conclusions: In this instance, at least, RCBS case sizing lube did not seem to have any bad effect on the cleaning/polishing medium at all. The cases were effectively cleaned of lube in about an hour of tumbling. After the lube was removed from the cases by tumbling them, the ground corncob medium appeared to be in the same condition as before: Loose, flakey, seemingly clean, and ready for the next session. The use of a dozen or so cotton cloth gun cleaning patches in with the tumbling medium may have contributed to maintaining the tumbling medium in usable condtion.
So there you are, FWIW. As a scientist, I have to hope someone else will independently try the same experiment, and duplicate my results.