People are confusing CDs and CD Ceramic.

Cds have an anodized surface that will wear off after a time. They are a little sketchy in the wet until the anodization wears off. The main reason I like them is that they last a bit longer mainly because of the time it takes for this to happen and they make it easier to clean the wheel as stuff does not stick to the rim as much.

Ceramics have a ceramic surface that lasts the life of the rim. They are very good in the wet but you need to use the specific brake pads to get good performance. They are great for really sloppy conditions that eat rims.