This brought back memories of my Dad back in the 70's hand washing his LP collection using dishwashing soap and racking them to air dry after patting them down with towels (no rubbing). We lived in Costa Rica at the time (avg year-round temp = 72F, so no AC), and mildew would grow on the LPs, so every 5 to 8 years, he had to wash them to ger rid of that stuff. They alwys sounded better after the wash.
CD's were less of an issue, but a few years ago I was packing up the household after my parents passed away, and sure enough, there was mildew growing on the CD's and some would skip. Washed them using the exact same procedure, voila, they play perfectly