On some of my older DVDs, there is some kind of odd trace around the edge of the disc... you can see it in the image where the light is reflected. I can wipe it off, but it's really sticky and takes some time to clean up. More sticky residue is all over the disc, so the trace only seems to be some accumulation of stuff that's all over the bottom side. Best thing that worked so far was soap and water and a bit of patience. Any idea what this is and how to prevent this for my other discs? Or is it a known issue for some weird kind of disc? Discs obviously don't work until they are cleaned.
Is there any residue in the boxes where they're stored? (I'm just thinking in case the plastic boxes are degrading a bit)
Nope... that would have been nice, replacing the boxes would be easy.