Over the years, I've seen some c-hings have early "made in HK" CDs (meaning 1991/1992) from PolyGram like that. I have one CD (許冠傑光榮引退匯群星) that has the same problem. I do not live in a 潮濕 area and the CD was never scratched. All my other CDs are ok....just that one has this problem.
我收藏的經典粵語流行曲CD (now over 1,500,000 views - as of April 9, 2014)