Several DVDs in my collection (usually Dual Layer) have "staining", which I've read is a cosmetic imperfection from when the discs are made... this is where it looks as if coffee was spilled on the disc, the plastic itself is not discolored. I have never had playback issues on these.
I recently purchased a DL DVD disc that has white spots on it that look exactly like dust. They're not littered all over the surface or in any uniform arrangement, yet they seem to be just under the disc (though they don't appear to be part of the actual data reflective layer), compressed air won't take them off.
I've never seen this though and I'm not sure what it is, but it looks exactly like little pieces of white dust, maybe even slight nicks in plastic but certainly not scratches. Importantly, playback is fine all the way through, but I've never seen this type of "defect" before and want to make sure this isn't part of a larger problem.
It does not look like any pictures I've seen of delamination or anything like that.
Anyone have any ideas?