Because it is covered in blackheads and moles. 
Not to be one to say "steroids" about everything, but...
I am lucky not to have many spots on my own body, but I assume that with age, I will gradually get more of them. Are the types of spots on John the types of spots people are born with, or are they [in part or in whole] age-related spots?
I know this question probably sounds dumb, but I don't have very many spots on my body, and I was never one to get pimples. So I don't know what spots on a person are blackheads versus pimples versus moles. I can somewhat distinguish them [pimples being the most obvious], but in John's case, I wasn't sure what they were.