IME, the black spots will come and go and the RD age. I remember the first time I saw the black spots on mine when she was younger I kind of freaked out. I thought she was sick or something. Does anyone out there know why this happens? I never got a good answer to this.
As far as becoming all orange when they are adults that is not always the case. However, as a general rule they are orange when the reach adulthood.