Many Hoya leaves have varying levels of white, or silver speckles. Some plants may have a large amount of speckling, while others have small amounts of random speckling and maybe not even on every leaf. I think cultural conditions can cause the plant to lose the speckling just like some variegated plants lose the variegation over time. I had a Hoya carnosa that eventually lost all speckling and the leaves were solid green. I also had two really large and old variegated Krimson Princess and Krimson Queen Hoya plants that over time lost every bit of variegation and reverted back to solid green. I think it has to do with age, light, temperature etc.
