"Reading about Seborrheic Dermatitis on wikipedia and the potential link to the Malassezia yeast. It usually presents in areas rich in sebum, which as many people know, the lips do not have sebaceous glands. However sebum does reach the lips from the area around the lips."
I read sebaceous glands were the same thing as fordyce spots. Perhaps most people do not have sebaceous glands (fordyce spots) on lips, but problems arise when they do.