I can only tell you about medieval western Europe - there and then, acne was of course not considered to be attractive, and clear skin was preferred, but a smooth complexion was much rarer. This was mostly due to the prevalence of smallpox, a disease which most people would have gotten at some point and often retained heavy facial scarring from. Acne wouldn't have been much of a big deal on top of an already pocked face. Sidenote: the reason we have the idea of milkmaids being beautiful now is because they were one of the only populations generally unaffected by smallpox outbreaks, since they were effectively vaccinated due to their close contact with cows, and thus, cowpox.